diff --git a/opentracing-shim/src/opentracingshim/__init__.py b/opentracing-shim/src/opentracingshim/__init__.py
index 7c5066f44d1..c0f59de937a 100644
--- a/opentracing-shim/src/opentracingshim/__init__.py
+++ b/opentracing-shim/src/opentracingshim/__init__.py
@@ -61,12 +61,11 @@ def set_operation_name(self, operation_name):
         self._otel_span.update_name(operation_name)
         return self
 
-    def finish(self, finish_time=None):
-        self._otel_span.end()
-        # TODO: Handle finish_time. The OpenTelemetry API doesn't currently
-        # support setting end time on a span and we cannot assume that all
-        # OpenTelemetry Tracer implementations have an `end_time` field.
-        # https://github.com/open-telemetry/opentelemetry-python/issues/134
+    def finish(self, finish_time: float = None):
+        end_time = finish_time
+        if end_time is not None:
+            end_time = util.time_seconds_to_ns(finish_time)
+        self._otel_span.end(end_time=end_time)
 
     def set_tag(self, key, value):
         self._otel_span.set_attribute(key, value)
@@ -233,7 +232,14 @@ def start_span(
             for key, value in tags.items():
                 span.set_attribute(key, value)
 
-        span.start(start_time=start_time)
+        # The OpenTracing API expects time values to be `float` values which
+        # represent the number of seconds since the epoch. OpenTelemetry
+        # represents time values as nanoseconds since the epoch.
+        start_time_ns = start_time
+        if start_time_ns is not None:
+            start_time_ns = util.time_seconds_to_ns(start_time)
+
+        span.start(start_time=start_time_ns)
         context = SpanContextWrapper(span.get_context())
         return SpanWrapper(self, context, span)
 
diff --git a/opentracing-shim/src/opentracingshim/util.py b/opentracing-shim/src/opentracingshim/util.py
index 48a1a108c45..6f7b80fe020 100644
--- a/opentracing-shim/src/opentracingshim/util.py
+++ b/opentracing-shim/src/opentracingshim/util.py
@@ -28,6 +28,32 @@ def time_ns():
 DEFAULT_EVENT_NAME = "log"
 
 
+def time_seconds_to_ns(time_seconds: float) -> int:
+    """Converts a time value in seconds to a time value in nanoseconds.
+
+    `time_seconds` is a `float` as returned by `time.time()` which represents
+    the number of seconds since the epoch.
+
+    The returned value is an `int` representing the number of nanoseconds since
+    the epoch.
+    """
+
+    return int(time_seconds * 1e9)
+
+
+def time_seconds_from_ns(time_nanoseconds: int) -> float:
+    """Converts a time value in nanoseconds to a time value in seconds.
+
+    `time_nanoseconds` is an `int` representing the number of nanoseconds since
+    the epoch.
+
+    The returned value is a `float` representing the number of seconds since
+    the epoch.
+    """
+
+    return time_nanoseconds / 1e9
+
+
 def event_name_from_kv(key_values: dict) -> str:
     """A helper function which returns an event name from the given dict, or a
     default event name.
diff --git a/opentracing-shim/tests/test_shim.py b/opentracing-shim/tests/test_shim.py
index 2e2a71c8e7c..c9a9c06a720 100644
--- a/opentracing-shim/tests/test_shim.py
+++ b/opentracing-shim/tests/test_shim.py
@@ -12,6 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import time
 import unittest
 
 import opentracing
@@ -19,6 +20,7 @@
 import opentracingshim
 from opentelemetry import trace
 from opentelemetry.sdk.trace import Tracer
+from opentracingshim import util
 
 
 class TestShim(unittest.TestCase):
@@ -112,9 +114,20 @@ def test_explicit_span_finish(self):
     def test_explicit_start_time(self):
         """Test `start_time` argument."""
 
-        now = opentracingshim.util.time_ns()
+        now = time.time()
         with self.shim.start_active_span("TestSpan", start_time=now) as scope:
-            self.assertEqual(scope.span.unwrap().start_time, now)
+            result = util.time_seconds_from_ns(scope.span.unwrap().start_time)
+            self.assertEqual(result, now)
+
+    def test_explicit_end_time(self):
+        """Test `end_time` argument of `finish()` method."""
+
+        span = self.shim.start_span("TestSpan")
+        now = time.time()
+        span.finish(now)
+
+        end_time = util.time_seconds_from_ns(span.unwrap().end_time)
+        self.assertEqual(end_time, now)
 
     def test_explicit_span_activation(self):
         """Test manual activation and deactivation of a span."""
diff --git a/opentracing-shim/tests/test_util.py b/opentracing-shim/tests/test_util.py
index 3b2dabcc89f..99e0b61ddce 100644
--- a/opentracing-shim/tests/test_util.py
+++ b/opentracing-shim/tests/test_util.py
@@ -12,6 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import time
 import unittest
 
 from opentracingshim import util
@@ -35,3 +36,15 @@ def test_event_name_from_kv(self):
         # Test missing `event` field.
         res = util.event_name_from_kv({"foo": "bar"})
         self.assertEqual(res, util.DEFAULT_EVENT_NAME)
+
+    def test_time_seconds_to_ns(self):
+        time_seconds = time.time()
+        result = util.time_seconds_to_ns(time_seconds)
+
+        self.assertEqual(result, int(time_seconds * 1e9))
+
+    def test_time_seconds_from_ns(self):
+        time_nanoseconds = util.time_ns()
+        result = util.time_seconds_from_ns(time_nanoseconds)
+
+        self.assertEqual(result, time_nanoseconds / 1e9)