diff --git a/boards/avsextrem/drivers/avsextrem-smb380.c b/boards/avsextrem/drivers/avsextrem-smb380.c
index 22749c94b0..1803b8c686 100644
--- a/boards/avsextrem/drivers/avsextrem-smb380.c
+++ b/boards/avsextrem/drivers/avsextrem-smb380.c
@@ -158,7 +158,7 @@ static void SMB380_simple_interrupthandler(void)
     if (interruptTicksSMB380 >= sampleRateSMB380 - 1) {
         interruptTicksSMB380 = 0;
         wakeupmessage.type = MSG_TYPE_SMB380_WAKEUP;
-        msg_send(&wakeupmessage, simple_pid, 0);
+        msg_try_send(&wakeupmessage, simple_pid);
     }
     else {
         interruptTicksSMB380++;
@@ -566,7 +566,7 @@ void wakeUpRegisteredProcesses(void)
 
     while ((pointerNo < SMB380_RING_BUFF_MAX_THREADS) &&
            (PointerList[pointerNo] > 0)) {
-        msg_send(&wakeupmessage, PointerList[pointerNo], false);
+        msg_try_send(&wakeupmessage, PointerList[pointerNo]);
         pointerNo++;
     }
 }
diff --git a/core/msg.c b/core/msg.c
index 1d89344e3d..f73966eea5 100644
--- a/core/msg.c
+++ b/core/msg.c
@@ -199,7 +199,7 @@ int msg_send_receive(msg_t *m, msg_t *reply, kernel_pid_t target_pid)
 
     /* msg_send blocks until reply received */
 
-    return msg_send(m, target_pid, true);
+    return msg_send(m, target_pid);
 }
 
 int msg_reply(msg_t *m, msg_t *reply)
diff --git a/examples/ccn-lite-client/main.c b/examples/ccn-lite-client/main.c
index 22781bca49..bf807f638c 100644
--- a/examples/ccn-lite-client/main.c
+++ b/examples/ccn-lite-client/main.c
@@ -138,7 +138,7 @@ static void riot_ccn_relay_config(int argc, char **argv)
     msg_t m;
     m.content.value = atoi(argv[1]);
     m.type = CCNL_RIOT_CONFIG_CACHE;
-    msg_send(&m, _relay_pid, 1);
+    msg_send(&m, _relay_pid);
 }
 
 static void riot_ccn_transceiver_start(kernel_pid_t _relay_pid)
@@ -195,7 +195,7 @@ static void riot_ccn_relay_stop(int argc, char **argv)
     msg_t m;
     m.content.value = 0;
     m.type = CCNL_RIOT_HALT;
-    msg_send(&m, _relay_pid, 1);
+    msg_send(&m, _relay_pid);
 
     /* mark relay as not running */
     _relay_pid = 0;
@@ -240,7 +240,7 @@ static void riot_ccn_pit_test(int argc, char **argv)
         m.content.ptr = (char *) &rmsg;
         m.type = CCNL_RIOT_MSG;
 
-        msg_send(&m, _relay_pid, 1);
+        msg_send(&m, _relay_pid);
 
         if ((segment % 50) == 0) {
             vtimer_now(&now);
@@ -289,7 +289,7 @@ static void riot_ccn_populate(int argc, char **argv)
     msg_t m;
     m.content.value = 0;
     m.type = CCNL_RIOT_POPULATE;
-    msg_send(&m, _relay_pid, 1);
+    msg_send(&m, _relay_pid);
 }
 
 static void riot_ccn_stat(int argc, char **argv)
@@ -300,7 +300,7 @@ static void riot_ccn_stat(int argc, char **argv)
     msg_t m;
     m.content.value = 0;
     m.type = CCNL_RIOT_PRINT_STAT;
-    msg_send(&m, _relay_pid, 1);
+    msg_send(&m, _relay_pid);
 }
 
 static const shell_command_t sc[] = {
diff --git a/examples/ccn-lite-relay/main.c b/examples/ccn-lite-relay/main.c
index 0354933f91..4d12a9c121 100644
--- a/examples/ccn-lite-relay/main.c
+++ b/examples/ccn-lite-relay/main.c
@@ -58,7 +58,7 @@ void populate_cache(void)
     msg_t m;
     m.content.value = 0;
     m.type = CCNL_RIOT_POPULATE;
-    msg_send(&m, _relay_pid, 1);
+    msg_send(&m, _relay_pid);
 }
 
 void *second_thread(void *arg)
diff --git a/examples/rpl_udp/helper.c b/examples/rpl_udp/helper.c
index 5eeee08f4d..475932a019 100644
--- a/examples/rpl_udp/helper.c
+++ b/examples/rpl_udp/helper.c
@@ -138,7 +138,7 @@ void rpl_udp_ignore(int argc, char **argv)
     if (argc == 2) {
         a = atoi(argv[1]);
         printf("sending to transceiver (%" PRIkernel_pid "): %u\n", transceiver_pid, (*(uint8_t *)tcmd.data));
-        msg_send(&mesg, transceiver_pid, 1);
+        msg_send(&mesg, transceiver_pid);
     }
     else {
         printf("Usage: %s <addr>\n", argv[0]);
diff --git a/sys/net/ccn_lite/ccnl-ext-appserver.c b/sys/net/ccn_lite/ccnl-ext-appserver.c
index d33adccb58..73ac2f75af 100644
--- a/sys/net/ccn_lite/ccnl-ext-appserver.c
+++ b/sys/net/ccn_lite/ccnl-ext-appserver.c
@@ -52,7 +52,7 @@ static int appserver_sent_content(uint8_t *buf, int len, kernel_pid_t from)
     m.content.ptr = (char *) &rmsg;
     kernel_pid_t dest_pid = from;
     DEBUGMSG(1, "sending msg to pid=%" PRIkernel_pid "\n", dest_pid);
-    int ret = msg_send(&m, dest_pid, 1);
+    int ret = msg_send(&m, dest_pid);
     DEBUGMSG(1, "msg_reply returned: %d\n", ret);
     return ret;
 }
diff --git a/sys/net/ccn_lite/ccnl-riot-compat.c b/sys/net/ccn_lite/ccnl-riot-compat.c
index bbdc63b0b7..7edd6bfc83 100644
--- a/sys/net/ccn_lite/ccnl-riot-compat.c
+++ b/sys/net/ccn_lite/ccnl-riot-compat.c
@@ -95,7 +95,7 @@ int riot_send_msg(uint8_t *buf, uint16_t size, uint16_t to)
     m.type = CCNL_RIOT_MSG;
     m.content.ptr = (char *) rmsg;
     DEBUGMSG(1, "sending msg to pid=%" PRIkernel_pid "\n", to);
-    msg_send(&m, to, 1);
+    msg_send(&m, to);
 
     return size;
 }
@@ -105,7 +105,7 @@ void riot_send_nack(uint16_t to)
     msg_t m;
     m.type = CCNL_RIOT_NACK;
     DEBUGMSG(1, "sending NACK msg to pid=%" PRIkernel_pid"\n", to);
-    msg_send(&m, to, 0);
+    msg_try_send(&m, to);
 }
 
 void *ccnl_riot_relay_helper_start(void *);
diff --git a/sys/net/ccn_lite/util/ccnl-riot-client.c b/sys/net/ccn_lite/util/ccnl-riot-client.c
index 1c317b1b89..f33d7d1f29 100644
--- a/sys/net/ccn_lite/util/ccnl-riot-client.c
+++ b/sys/net/ccn_lite/util/ccnl-riot-client.c
@@ -67,7 +67,7 @@ int ccnl_riot_client_get(kernel_pid_t relay_pid, char *name, char *reply_buf)
         msg_t m, rep;
         m.content.ptr = (char *) &rmsg;
         m.type = CCNL_RIOT_MSG;
-        msg_send(&m, relay_pid, 1);
+        msg_send(&m, relay_pid);
 
         /* ######################################################################### */
 
@@ -131,7 +131,7 @@ int ccnl_riot_client_new_face(kernel_pid_t relay_pid, char *type, char *faceid,
     m.content.ptr = (char *) &rmsg;
     m.type = CCNL_RIOT_MSG;
     DEBUGMSG(1, "  sending face req to relay\n");
-    msg_send(&m, relay_pid, 1);
+    msg_send(&m, relay_pid);
 
     /* ######################################################################### */
 
@@ -160,7 +160,7 @@ int ccnl_riot_client_register_prefix(kernel_pid_t relay_pid, char *prefix, char
     m.content.ptr = (char *) &rmsg;
     m.type = CCNL_RIOT_MSG;
     DEBUGMSG(1, "  sending prefix req to relay\n");
-    msg_send(&m, relay_pid, 1);
+    msg_send(&m, relay_pid);
 
     /* ######################################################################### */
 
diff --git a/sys/net/network_layer/sixlowpan/border/border.c b/sys/net/network_layer/sixlowpan/border/border.c
index 09422b94ec..b53c456bec 100644
--- a/sys/net/network_layer/sixlowpan/border/border.c
+++ b/sys/net/network_layer/sixlowpan/border/border.c
@@ -113,7 +113,7 @@ void serial_reader_f(void)
 
                 if (conf_packet->conftype == BORDER_CONF_SYN) {
                     m.content.ptr = (char *)conf_packet;
-                    msg_send(&m, main_pid, 1);
+                    msg_send(&m, main_pid);
                     continue;
                 }
             }
diff --git a/sys/net/network_layer/sixlowpan/border/flowcontrol.c b/sys/net/network_layer/sixlowpan/border/flowcontrol.c
index 2b7478d96f..19240a86d2 100644
--- a/sys/net/network_layer/sixlowpan/border/flowcontrol.c
+++ b/sys/net/network_layer/sixlowpan/border/flowcontrol.c
@@ -43,7 +43,7 @@ ipv6_addr_t init_threeway_handshake(void)
     border_syn_packet_t *syn;
     msg_t m;
     m.content.ptr = NULL;
-    msg_send(&m, border_get_serial_reader(), 1);
+    msg_send(&m, border_get_serial_reader());
     msg_receive(&m);
 
     syn = (border_syn_packet_t *)m.content.ptr;
diff --git a/sys/net/network_layer/sixlowpan/ip.c b/sys/net/network_layer/sixlowpan/ip.c
index 7f080bdbc0..a61a1d1d5f 100644
--- a/sys/net/network_layer/sixlowpan/ip.c
+++ b/sys/net/network_layer/sixlowpan/ip.c
@@ -262,7 +262,7 @@ int icmpv6_demultiplex(const icmpv6_hdr_t *hdr)
             if (_rpl_process_pid != KERNEL_PID_UNDEF) {
                 msg_t m_send;
                 m_send.content.ptr = (char *) &hdr->code;
-                msg_send(&m_send, _rpl_process_pid, 1);
+                msg_send(&m_send, _rpl_process_pid);
             }
             else {
                 DEBUG("INFO: no RPL handler registered\n");
@@ -371,7 +371,7 @@ void *ipv6_process(void *arg)
                 msg_t m_send;
                 m_send.type = IPV6_PACKET_RECEIVED;
                 m_send.content.ptr = (char *) ipv6_buf;
-                msg_send(&m_send, sixlowip_reg[i], 1);
+                msg_send(&m_send, sixlowip_reg[i]);
             }
         }
 
diff --git a/sys/net/network_layer/sixlowpan/lowpan.c b/sys/net/network_layer/sixlowpan/lowpan.c
index f7bdabef98..6e85a3514c 100644
--- a/sys/net/network_layer/sixlowpan/lowpan.c
+++ b/sys/net/network_layer/sixlowpan/lowpan.c
@@ -795,7 +795,7 @@ void lowpan_read(uint8_t *data, uint8_t length, net_if_eui64_t *s_addr,
             current_frame.length = length;
             current_frame.data = data;
             m_send.content.ptr = (char *) &current_frame;
-            msg_send(&m_send, sixlowpan_reg[i], 1);
+            msg_send(&m_send, sixlowpan_reg[i]);
         }
     }
 
diff --git a/sys/net/transport_layer/socket_base/msg_help.c b/sys/net/transport_layer/socket_base/msg_help.c
index 1dbe1e4ed3..4b9f6e6179 100644
--- a/sys/net/transport_layer/socket_base/msg_help.c
+++ b/sys/net/transport_layer/socket_base/msg_help.c
@@ -43,7 +43,11 @@ int socket_base_net_msg_reply(msg_t *m, msg_t *reply, uint16_t message)
 int socket_base_net_msg_send(msg_t *m, kernel_pid_t pid, bool block, uint16_t message)
 {
     m->type = message;
-    return msg_send(m, pid, block);
+    if (block) {
+       return  msg_send(m, pid);
+    } else {
+        return msg_try_send(m, pid);
+    }
 }
 
 int socket_base_net_msg_send_recv(msg_t *m, msg_t *reply, kernel_pid_t pid, uint16_t message)
diff --git a/sys/net/transport_layer/tcp/tcp.c b/sys/net/transport_layer/tcp/tcp.c
index de35b5316d..65b0bc2e3f 100644
--- a/sys/net/transport_layer/tcp/tcp.c
+++ b/sys/net/transport_layer/tcp/tcp.c
@@ -477,12 +477,12 @@ void handle_tcp_ack_packet(ipv6_hdr_t *ipv6_header, tcp_hdr_t *tcp_header,
     if (tcp_socket->socket_values.tcp_control.state == TCP_LAST_ACK) {
         uint8_t target_pid = tcp_socket->recv_pid;
         memset(tcp_socket, 0, sizeof(socket_internal_t));
-        msg_send(&m_send_tcp, target_pid, 0);
+        msg_try_send(&m_send_tcp, target_pid);
         return;
     }
     else if (tcp_socket->socket_values.tcp_control.state == TCP_CLOSING) {
-        msg_send(&m_send_tcp, tcp_socket->recv_pid, 0);
-        msg_send(&m_send_tcp, tcp_socket->send_pid, 0);
+        msg_try_send(&m_send_tcp, tcp_socket->recv_pid);
+        msg_try_send(&m_send_tcp, tcp_socket->send_pid);
         return;
     }
     else if (get_waiting_connection_socket(tcp_socket->socket_id, ipv6_header,
@@ -613,8 +613,8 @@ void handle_tcp_fin_ack_packet(ipv6_hdr_t *ipv6_header, tcp_hdr_t *tcp_header,
 
     send_tcp(tcp_socket, current_tcp_packet, temp_ipv6_header, TCP_ACK, 0);
 
-    msg_send(&m_send, tcp_socket->send_pid, 0);
-    msg_send(&m_send, tcp_socket->recv_pid, 0);
+    msg_try_send(&m_send, tcp_socket->send_pid);
+    msg_try_send(&m_send, tcp_socket->recv_pid);
 }
 
 void handle_tcp_no_flags_packet(ipv6_hdr_t *ipv6_header, tcp_hdr_t *tcp_header,
diff --git a/sys/shell/commands/sc_transceiver.c b/sys/shell/commands/sc_transceiver.c
index b11edc3845..17ab19c0a0 100644
--- a/sys/shell/commands/sc_transceiver.c
+++ b/sys/shell/commands/sc_transceiver.c
@@ -285,7 +285,7 @@ void _transceiver_monitor_handler(int argc, char **argv)
     mesg.content.ptr = (char *) &tcmd;
     mesg.type = SET_MONITOR;
 
-    msg_send(&mesg, transceiver_pid, 1);
+    msg_send(&mesg, transceiver_pid);
 }
 
 /* checked for type safety */
diff --git a/sys/transceiver/transceiver.c b/sys/transceiver/transceiver.c
index ab8e615f2f..87b46310ad 100644
--- a/sys/transceiver/transceiver.c
+++ b/sys/transceiver/transceiver.c
@@ -503,7 +503,7 @@ static void receive_packet(uint16_t type, uint8_t pos)
             m.content.ptr = (char *) &(transceiver_buffer[transceiver_buffer_pos]);
             DEBUG("transceiver: Notify thread %" PRIkernel_pid "\n", reg[i].pid);
 
-            if (msg_send(&m, reg[i].pid, false) && (m.type != ENOBUFFER)) {
+            if (msg_try_send(&m, reg[i].pid) && (m.type != ENOBUFFER)) {
                 transceiver_buffer[transceiver_buffer_pos].processing++;
             }
             else {
diff --git a/tests/nativenet/main.c b/tests/nativenet/main.c
index ddc0d96399..5201bf3f10 100644
--- a/tests/nativenet/main.c
+++ b/tests/nativenet/main.c
@@ -124,7 +124,7 @@ void sender(void)
         snd_buffer[1] = i & 0x00FF;
         p.data = snd_buffer;
         i++;
-        msg_send(&mesg, transceiver_pid, 1);
+        msg_send(&mesg, transceiver_pid);
         hwtimer_wait(HWTIMER_TICKS(SENDING_DELAY));
     }
 }
diff --git a/tests/periph_uart_int/main.c b/tests/periph_uart_int/main.c
index 3c272bc483..19c71845ec 100644
--- a/tests/periph_uart_int/main.c
+++ b/tests/periph_uart_int/main.c
@@ -61,7 +61,7 @@ void rx(void *ptr, char data)
 
     ringbuffer_add_one(&rx_buf, data);
     if (data == '\n') {
-        msg_send(&msg, main_pid, 1);
+        msg_send(&msg, main_pid);
     }
 }
 
diff --git a/tests/queue_fairness/main.c b/tests/queue_fairness/main.c
index 40d864a504..914354e784 100644
--- a/tests/queue_fairness/main.c
+++ b/tests/queue_fairness/main.c
@@ -42,7 +42,7 @@ static void *child_fun(void *arg)
         msg_t m;
         m.type = i + 1;
         m.content.ptr = (void *) sched_active_thread->name;
-        msg_send(&m, parent_pid, true);
+        msg_send(&m, parent_pid);
     }
 
     printf("End of %s.\n", sched_active_thread->name);
diff --git a/tests/thread_cooperation/main.c b/tests/thread_cooperation/main.c
index f5097027a5..ff42ef8942 100644
--- a/tests/thread_cooperation/main.c
+++ b/tests/thread_cooperation/main.c
@@ -50,7 +50,7 @@ void *run(void *arg)
 
     msg_t final;
     final.content.value = me;
-    int err = msg_send(&final, main_id, 1);
+    int err = msg_send(&final, main_id);
 
     if (err < 0) {
         printf("[!!!] Failed to send message from %d to main\n", me);
@@ -79,7 +79,7 @@ int main(void)
         else {
             args[i].content.value = i + 1;
 
-            int err = msg_send(&args[i], ths[i], 1);
+            int err = msg_send(&args[i], ths[i]);
             if (err < 0) {
                 printf("[!!!] Sending message to thread %d failed\n", ths[i]);
             }
diff --git a/tests/thread_msg/main.c b/tests/thread_msg/main.c
index 8cdef7d725..a2aebdfceb 100644
--- a/tests/thread_msg/main.c
+++ b/tests/thread_msg/main.c
@@ -76,7 +76,7 @@ void *thread3(void *arg)
         msg_t msg;
         msg.content.value = i;
         printf("T3 i=%d\n", i);
-        msg_send(&msg, p1, 1);
+        msg_send(&msg, p1);
     }
     return NULL;
 }
diff --git a/tests/thread_msg_block_w_queue/main.c b/tests/thread_msg_block_w_queue/main.c
index f322324410..24df29838d 100644
--- a/tests/thread_msg_block_w_queue/main.c
+++ b/tests/thread_msg_block_w_queue/main.c
@@ -39,7 +39,7 @@ void *thread1(void *arg)
     memset(&msg, 1, sizeof(msg_t));
 
     /* step 1: send asynchonously */
-    msg_send(&msg, p_main, 0);
+    msg_try_send(&msg, p_main);
 
     /* step 2: send message, turning its status into STATUS_REPLY_BLOCKED */
     msg_send_receive(&msg, &reply, p_main);
diff --git a/tests/thread_msg_block_wo_queue/main.c b/tests/thread_msg_block_wo_queue/main.c
index 21f946ed9d..1808f2edcd 100644
--- a/tests/thread_msg_block_wo_queue/main.c
+++ b/tests/thread_msg_block_wo_queue/main.c
@@ -39,7 +39,7 @@ void *thread1(void *arg)
     memset(&msg, 1, sizeof(msg_t));
 
     /* step 1: send asynchonously */
-    msg_send(&msg, p_main, 0);
+    msg_try_send(&msg, p_main);
 
     /* step 2: send message, turning its status into STATUS_REPLY_BLOCKED */
     msg_send_receive(&msg, &reply, p_main);
diff --git a/tests/thread_msg_seq/main.c b/tests/thread_msg_seq/main.c
index 239f2f1f97..717b0e4a1e 100644
--- a/tests/thread_msg_seq/main.c
+++ b/tests/thread_msg_seq/main.c
@@ -43,7 +43,7 @@ void *sub_thread(void *arg)
 
     msg.content.ptr = (char*)thread_getname(pid);
 
-    msg_send(&msg, p_main, true);
+    msg_send(&msg, p_main);
 
     printf("THREAD %s (pid:%" PRIkernel_pid ") end.\n", thread_getname(pid), pid);
 
diff --git a/tests/vtimer_msg/main.c b/tests/vtimer_msg/main.c
index 93969956c5..82800dc571 100644
--- a/tests/vtimer_msg/main.c
+++ b/tests/vtimer_msg/main.c
@@ -103,11 +103,11 @@ int main(void)
 
     puts("sending 1st msg");
     m.content.ptr = (char *) &msg_a;
-    msg_send(&m, pid, false);
+    msg_try_send(&m, pid);
 
     puts("sending 2nd msg");
     m.content.ptr = (char *) &msg_b;
-    msg_send(&m, pid, false);
+    msg_try_send(&m, pid);
 
     kernel_pid_t pid2 = thread_create(
                    timer_stack_local,
@@ -122,6 +122,6 @@ int main(void)
 
     while (1) {
         vtimer_sleep(sleep);
-        msg_send(&m, pid2, 0);
+        msg_try_send(&m, pid2);
     }
 }
diff --git a/tests/vtimer_msg_diff/main.c b/tests/vtimer_msg_diff/main.c
index 4f6de2cd6c..c4b5ce5d03 100644
--- a/tests/vtimer_msg_diff/main.c
+++ b/tests/vtimer_msg_diff/main.c
@@ -115,7 +115,7 @@ int main(void)
     for (unsigned i = 0; i < sizeof(timer_msgs)/sizeof(struct timer_msg); i++) {
         printf("Sending timer msg %u...\n", i);
         m.content.ptr = (char *) &timer_msgs[i];
-        msg_send(&m, pid, false);
+        msg_try_send(&m, pid);
     }
 
     return 0;