diff --git a/README.md b/README.md
index 7f8dee2..b7aa3f9 100644
--- a/README.md
+++ b/README.md
@@ -73,8 +73,10 @@ To receive data with a `GmiiSink`, call `recv()`.  Call `wait()` to wait for new
 
 #### Methods
 
-* `send(frame)`: send _frame_ (source)
-* `recv()`: receive a frame as a `GmiiFrame` (sink)
+* `send(frame)`: send _frame_ (blocking) (source)
+* `send_nowait(frame)`: send _frame_ (non-blocking) (source)
+* `recv()`: receive a frame as a `GmiiFrame` (blocking) (sink)
+* `recv_nowait()`: receive a frame as a `GmiiFrame` (non-blocking) (sink)
 * `count()`: returns the number of items in the queue (all)
 * `empty()`: returns _True_ if the queue is empty (all)
 * `idle()`: returns _True_ if no transfer is in progress (all) or if the queue is not empty (source)
@@ -147,8 +149,10 @@ To receive data with an `RgmiiSink`, call `recv()`.  Call `wait()` to wait for n
 
 #### Methods
 
-* `send(frame)`: send _frame_ (source)
-* `recv()`: receive a frame as a `GmiiFrame` (sink)
+* `send(frame)`: send _frame_ (blocking) (source)
+* `send_nowait(frame)`: send _frame_ (non-blocking) (source)
+* `recv()`: receive a frame as a `GmiiFrame` (blocking) (sink)
+* `recv_nowait()`: receive a frame as a `GmiiFrame` (non-blocking) (sink)
 * `count()`: returns the number of items in the queue (all)
 * `empty()`: returns _True_ if the queue is empty (all)
 * `idle()`: returns _True_ if no transfer is in progress (all) or if the queue is not empty (source)
@@ -198,8 +202,10 @@ To receive data with an `XgmiiSink`, call `recv()`.  Call `wait()` to wait for n
 
 #### Methods
 
-* `send(frame)`: send _frame_ (source)
-* `recv()`: receive a frame as an `XgmiiFrame` (sink)
+* `send(frame)`: send _frame_ (blocking) (source)
+* `send_nowait(frame)`: send _frame_ (non-blocking) (source)
+* `recv()`: receive a frame as an `XgmiiFrame` (blocking) (sink)
+* `recv_nowait()`: receive a frame as an `XgmiiFrame` (non-blocking) (sink)
 * `count()`: returns the number of items in the queue (all)
 * `empty()`: returns _True_ if the queue is empty (all)
 * `idle()`: returns _True_ if no transfer is in progress (all) or if the queue is not empty (source)
diff --git a/cocotbext/eth/gmii.py b/cocotbext/eth/gmii.py
index e0adfc7..0dd129a 100644
--- a/cocotbext/eth/gmii.py
+++ b/cocotbext/eth/gmii.py
@@ -156,7 +156,10 @@ class GmiiSource(object):
 
         cocotb.fork(self._run())
 
-    def send(self, frame):
+    async def send(self, frame):
+        self.send_nowait(frame)
+
+    def send_nowait(self, frame):
         frame = GmiiFrame(frame)
         self.queue_occupancy_bytes += len(frame)
         self.queue_occupancy_frames += 1
@@ -278,7 +281,13 @@ class GmiiSink(object):
 
         cocotb.fork(self._run())
 
-    def recv(self):
+    async def recv(self, compact=True):
+        while self.empty():
+            self.sync.clear()
+            await self.sync.wait()
+        return self.recv_nowait(compact)
+
+    def recv_nowait(self, compact=True):
         if self.queue:
             frame = self.queue.popleft()
             self.queue_occupancy_bytes -= len(frame)
diff --git a/cocotbext/eth/rgmii.py b/cocotbext/eth/rgmii.py
index 731a833..61bca69 100644
--- a/cocotbext/eth/rgmii.py
+++ b/cocotbext/eth/rgmii.py
@@ -72,7 +72,10 @@ class RgmiiSource(object):
 
         cocotb.fork(self._run())
 
-    def send(self, frame):
+    async def send(self, frame):
+        self.send_nowait(frame)
+
+    def send_nowait(self, frame):
         frame = GmiiFrame(frame)
         self.queue_occupancy_bytes += len(frame)
         self.queue_occupancy_frames += 1
@@ -200,7 +203,13 @@ class RgmiiSink(object):
 
         cocotb.fork(self._run())
 
-    def recv(self):
+    async def recv(self, compact=True):
+        while self.empty():
+            self.sync.clear()
+            await self.sync.wait()
+        return self.recv_nowait(compact)
+
+    def recv_nowait(self, compact=True):
         if self.queue:
             frame = self.queue.popleft()
             self.queue_occupancy_bytes -= len(frame)
diff --git a/cocotbext/eth/xgmii.py b/cocotbext/eth/xgmii.py
index 327ef57..9ef4c26 100644
--- a/cocotbext/eth/xgmii.py
+++ b/cocotbext/eth/xgmii.py
@@ -163,7 +163,10 @@ class XgmiiSource(object):
 
         cocotb.fork(self._run())
 
-    def send(self, frame):
+    async def send(self, frame):
+        self.send_nowait(frame)
+
+    def send_nowait(self, frame):
         frame = XgmiiFrame(frame)
         self.queue_occupancy_bytes += len(frame)
         self.queue_occupancy_frames += 1
@@ -305,7 +308,13 @@ class XgmiiSink(object):
 
         cocotb.fork(self._run())
 
-    def recv(self):
+    async def recv(self, compact=True):
+        while self.empty():
+            self.sync.clear()
+            await self.sync.wait()
+        return self.recv_nowait(compact)
+
+    def recv_nowait(self, compact=True):
         if self.queue:
             frame = self.queue.popleft()
             self.queue_occupancy_bytes -= len(frame)
diff --git a/tests/gmii/test_gmii.py b/tests/gmii/test_gmii.py
index ac6c136..c6d7f4b 100644
--- a/tests/gmii/test_gmii.py
+++ b/tests/gmii/test_gmii.py
@@ -103,11 +103,10 @@ async def run_test(dut, payload_lengths=None, payload_data=None, ifg=12, enable_
 
     for test_data in test_frames:
         test_frame = GmiiFrame.from_payload(test_data)
-        tb.source.send(test_frame)
+        await tb.source.send(test_frame)
 
     for test_data in test_frames:
-        await tb.sink.wait()
-        rx_frame = tb.sink.recv()
+        rx_frame = await tb.sink.recv()
 
         assert rx_frame.get_payload() == test_data
         assert rx_frame.check_fcs()
diff --git a/tests/rgmii/test_rgmii.py b/tests/rgmii/test_rgmii.py
index 57fafb7..d4bf262 100644
--- a/tests/rgmii/test_rgmii.py
+++ b/tests/rgmii/test_rgmii.py
@@ -101,11 +101,10 @@ async def run_test(dut, payload_lengths=None, payload_data=None, ifg=12, enable_
 
     for test_data in test_frames:
         test_frame = GmiiFrame.from_payload(test_data)
-        tb.source.send(test_frame)
+        await tb.source.send(test_frame)
 
     for test_data in test_frames:
-        await tb.sink.wait()
-        rx_frame = tb.sink.recv()
+        rx_frame = await tb.sink.recv()
 
         assert rx_frame.get_payload() == test_data
         assert rx_frame.check_fcs()
diff --git a/tests/xgmii/test_xgmii.py b/tests/xgmii/test_xgmii.py
index 28e2493..c96e648 100644
--- a/tests/xgmii/test_xgmii.py
+++ b/tests/xgmii/test_xgmii.py
@@ -103,11 +103,10 @@ async def run_test(dut, payload_lengths=None, payload_data=None, ifg=12, enable_
 
     for test_data in test_frames:
         test_frame = XgmiiFrame.from_payload(test_data)
-        tb.source.send(test_frame)
+        await tb.source.send(test_frame)
 
     for test_data in test_frames:
-        await tb.sink.wait()
-        rx_frame = tb.sink.recv()
+        rx_frame = await tb.sink.recv()
 
         assert rx_frame.get_payload() == test_data
         assert rx_frame.check_fcs()
@@ -142,11 +141,10 @@ async def run_test_alignment(dut, payload_data=None, ifg=12, enable_dic=True,
 
         for test_data in test_frames:
             test_frame = XgmiiFrame.from_payload(test_data)
-            tb.source.send(test_frame)
+            await tb.source.send(test_frame)
 
         for test_data in test_frames:
-            await tb.sink.wait()
-            rx_frame = tb.sink.recv()
+            rx_frame = await tb.sink.recv()
 
             assert rx_frame.get_payload() == test_data
             assert rx_frame.check_fcs()