diff --git a/moto/ec2/models.py b/moto/ec2/models.py
index 5337fe563..13d70a086 100644
--- a/moto/ec2/models.py
+++ b/moto/ec2/models.py
@@ -280,6 +280,7 @@ class Instance(BotoInstance, TaggedEC2Resource):
         self.instance_type = kwargs.get("instance_type", "m1.small")
         self.subnet_id = kwargs.get("subnet_id")
         self.key_name = kwargs.get("key_name")
+        self.source_dest_check = "true"
 
         self.block_device_mapping = BlockDeviceMapping()
         self.block_device_mapping['/dev/sda1'] = BlockDeviceType(volume_id=random_volume_id())
diff --git a/moto/ec2/responses/elastic_network_interfaces.py b/moto/ec2/responses/elastic_network_interfaces.py
index dc952cd05..d3f7388bc 100644
--- a/moto/ec2/responses/elastic_network_interfaces.py
+++ b/moto/ec2/responses/elastic_network_interfaces.py
@@ -72,7 +72,9 @@ CREATE_NETWORK_INTERFACE_RESPONSE = """
         {% if eni.private_ip_address %}
           <privateIpAddress>{{ eni.private_ip_address }}</privateIpAddress>
         {% endif %}
-        <sourceDestCheck>true</sourceDestCheck>
+        {% if eni.instance %}
+          <sourceDestCheck>{{ eni.instance.source_dest_check }}</sourceDestCheck>
+        {% endif %}
         <groupSet>
         {% for group in eni.group_set %}
             <item>
@@ -114,7 +116,9 @@ DESCRIBE_NETWORK_INTERFACES_RESPONSE = """<DescribeNetworkInterfacesResponse xml
              <privateIpAddress>{{ eni.private_ip_address }}</privateIpAddress>
            {% endif %}
            <privateDnsName>ip-10-0-0-134.us-west-2.compute.internal</privateDnsName>
-           <sourceDestCheck>true</sourceDestCheck>
+           {% if eni.instance %}
+             <sourceDestCheck>{{ eni.instance.source_dest_check }}</sourceDestCheck>
+           {% endif %}
            <groupSet>
            {% for group in eni.group_set %}
                <item>
diff --git a/moto/ec2/responses/instances.py b/moto/ec2/responses/instances.py
index 70f19a8f2..49050f9d6 100644
--- a/moto/ec2/responses/instances.py
+++ b/moto/ec2/responses/instances.py
@@ -206,7 +206,7 @@ EC2_RUN_INSTANCES = """<RunInstancesResponse xmlns="http://ec2.amazonaws.com/doc
           {% else %}
             <subnetId>{{ instance.subnet_id }}</subnetId>
           {% endif %}
-          <sourceDestCheck>true</sourceDestCheck>
+          <sourceDestCheck>{{ instance.source_dest_check }}</sourceDestCheck>
           <groupSet>
              {% for group in instance.dynamic_group_list %}
              <item>
@@ -235,7 +235,7 @@ EC2_RUN_INSTANCES = """<RunInstancesResponse xmlns="http://ec2.amazonaws.com/doc
                 <status>in-use</status>
                 <macAddress>1b:2b:3c:4d:5e:6f</macAddress>
                 <privateIpAddress>{{ nic.private_ip_address }}</privateIpAddress>
-                <sourceDestCheck>true</sourceDestCheck>
+                <sourceDestCheck>{{ instance.source_dest_check }}</sourceDestCheck>
                 <groupSet>
                   {% for group in nic.group_set %}
                   <item>
@@ -328,7 +328,7 @@ EC2_DESCRIBE_INSTANCES = """<DescribeInstancesResponse xmlns='http://ec2.amazona
                       <ipAddress>46.51.219.63</ipAddress>
                       {% endif %}
                     {% endif %}
-                    <sourceDestCheck>true</sourceDestCheck>
+                    <sourceDestCheck>{{ instance.source_dest_check }}</sourceDestCheck>
                     <groupSet>
                       {% for group in instance.dynamic_group_list %}
                       <item>
@@ -380,7 +380,7 @@ EC2_DESCRIBE_INSTANCES = """<DescribeInstancesResponse xmlns='http://ec2.amazona
                           <status>in-use</status>
                           <macAddress>1b:2b:3c:4d:5e:6f</macAddress>
                           <privateIpAddress>{{ nic.private_ip_address }}</privateIpAddress>
-                          <sourceDestCheck>true</sourceDestCheck>
+                          <sourceDestCheck>{{ instance.source_dest_check }}</sourceDestCheck>
                           <groupSet>
                             {% for group in nic.group_set %}
                             <item>
diff --git a/tests/test_ec2/test_instances.py b/tests/test_ec2/test_instances.py
index 955ce0477..98740a8ae 100644
--- a/tests/test_ec2/test_instances.py
+++ b/tests/test_ec2/test_instances.py
@@ -246,6 +246,40 @@ def test_instance_attribute_user_data():
     instance_attribute.get("userData").should.equal("this is my user data")
 
 
+@mock_ec2
+def test_instance_attribute_source_dest_check():
+    conn = boto.connect_ec2('the_key', 'the_secret')
+    reservation = conn.run_instances('ami-1234abcd')
+    instance = reservation.instances[0]
+
+    # Default value is true
+    instance.sourceDestCheck.should.equal('true')
+
+    instance_attribute = instance.get_attribute("sourceDestCheck")
+    instance_attribute.should.be.a(InstanceAttribute)
+    instance_attribute.get("sourceDestCheck").should.equal(True)
+
+    # Set to false (note: Boto converts bool to string, eg 'false')
+    instance.modify_attribute("sourceDestCheck", False)
+
+    instance.update()
+    instance.sourceDestCheck.should.equal('false')
+
+    instance_attribute = instance.get_attribute("sourceDestCheck")
+    instance_attribute.should.be.a(InstanceAttribute)
+    instance_attribute.get("sourceDestCheck").should.equal(False)
+
+    # Set back to true
+    instance.modify_attribute("sourceDestCheck", True)
+
+    instance.update()
+    instance.sourceDestCheck.should.equal('true')
+
+    instance_attribute = instance.get_attribute("sourceDestCheck")
+    instance_attribute.should.be.a(InstanceAttribute)
+    instance_attribute.get("sourceDestCheck").should.equal(True)
+
+
 @mock_ec2
 def test_user_data_with_run_instance():
     user_data = b"some user data"