diff --git a/moto/ec2/models.py b/moto/ec2/models.py
index 5579c8744..c9e76a14c 100644
--- a/moto/ec2/models.py
+++ b/moto/ec2/models.py
@@ -1659,6 +1659,14 @@ class RouteTableBackend(object):
                 return route_table.associations.pop(association_id, None)
         raise InvalidAssociationIdError(association_id)
 
+    def replace_route_table_association(self, association_id, route_table_id):
+        route_tables_by_association_id = ec2_backend.get_all_route_tables(filters={'association.route-table-association-id':[association_id]})
+        if not route_tables_by_association_id:
+            raise InvalidAssociationIdError(association_id)
+        previous_route_table = route_tables_by_association_id[0]
+        subnet_id = previous_route_table.associations.pop(association_id,None)
+        return self.associate_route_table(route_table_id, subnet_id)
+
 
 class Route(object):
     def __init__(self, route_table, destination_cidr_block, local=False,
diff --git a/moto/ec2/responses/route_tables.py b/moto/ec2/responses/route_tables.py
index 58f9db949..4d73bc917 100644
--- a/moto/ec2/responses/route_tables.py
+++ b/moto/ec2/responses/route_tables.py
@@ -83,7 +83,11 @@ class RouteTables(BaseResponse):
         return template.render()
 
     def replace_route_table_association(self):
-        raise NotImplementedError('RouteTables(AmazonVPC).replace_route_table_association is not yet implemented')
+        route_table_id = self.querystring.get('RouteTableId')[0]
+        association_id = self.querystring.get('AssociationId')[0]
+        new_association_id = ec2_backend.replace_route_table_association(association_id, route_table_id)
+        template = Template(REPLACE_ROUTE_TABLE_ASSOCIATION_RESPONSE)
+        return template.render(association_id=new_association_id)
 
 
 CREATE_ROUTE_RESPONSE = """
@@ -201,3 +205,10 @@ DISASSOCIATE_ROUTE_TABLE_RESPONSE = """
    <return>true</return>
 </DisassociateRouteTableResponse>
 """
+
+REPLACE_ROUTE_TABLE_ASSOCIATION_RESPONSE = """
+<ReplaceRouteTableAssociationResponse xmlns="http://ec2.amazonaws.com/doc/2014-06-15/">
+   <requestId>59dbff89-35bd-4eac-99ed-be587EXAMPLE</requestId>
+   <newAssociationId>{{ association_id }}</newAssociationId>
+</ReplaceRouteTableAssociationResponse>
+"""
diff --git a/tests/test_ec2/test_route_tables.py b/tests/test_ec2/test_route_tables.py
index f5ed8caf7..919410c14 100644
--- a/tests/test_ec2/test_route_tables.py
+++ b/tests/test_ec2/test_route_tables.py
@@ -213,6 +213,72 @@ def test_route_table_associations():
     cm.exception.request_id.should_not.be.none
 
 
+@mock_ec2
+def test_route_table_replace_route_table_association():
+    """
+      Note: Boto has deprecated replace_route_table_assocation (which returns status)
+        and now uses replace_route_table_assocation_with_assoc (which returns association ID).
+    """
+    conn = boto.connect_vpc('the_key', 'the_secret')
+    vpc = conn.create_vpc("10.0.0.0/16")
+    subnet = conn.create_subnet(vpc.id, "10.0.0.0/18")
+    route_table1 = conn.create_route_table(vpc.id)
+    route_table2 = conn.create_route_table(vpc.id)
+
+    all_route_tables = conn.get_all_route_tables()
+    all_route_tables.should.have.length_of(3)
+
+    # Refresh
+    route_table1 = conn.get_all_route_tables(route_table1.id)[0]
+    route_table1.associations.should.have.length_of(0)
+
+    # Associate
+    association_id1 = conn.associate_route_table(route_table1.id, subnet.id)
+
+    # Refresh
+    route_table1 = conn.get_all_route_tables(route_table1.id)[0]
+    route_table2 = conn.get_all_route_tables(route_table2.id)[0]
+
+    # Validate
+    route_table1.associations.should.have.length_of(1)
+    route_table2.associations.should.have.length_of(0)
+
+    route_table1.associations[0].id.should.equal(association_id1)
+    route_table1.associations[0].main.should.equal(False)
+    route_table1.associations[0].route_table_id.should.equal(route_table1.id)
+    route_table1.associations[0].subnet_id.should.equal(subnet.id)
+
+    # Replace Association
+    association_id2 = conn.replace_route_table_association_with_assoc(association_id1, route_table2.id)
+
+    # Refresh
+    route_table1 = conn.get_all_route_tables(route_table1.id)[0]
+    route_table2 = conn.get_all_route_tables(route_table2.id)[0]
+
+    # Validate
+    route_table1.associations.should.have.length_of(0)
+    route_table2.associations.should.have.length_of(1)
+
+    route_table2.associations[0].id.should.equal(association_id2)
+    route_table2.associations[0].main.should.equal(False)
+    route_table2.associations[0].route_table_id.should.equal(route_table2.id)
+    route_table2.associations[0].subnet_id.should.equal(subnet.id)
+
+    # Error: Replace association with invalid association ID
+    with assert_raises(EC2ResponseError) as cm:
+        conn.replace_route_table_association_with_assoc("rtbassoc-1234abcd", route_table1.id)
+    cm.exception.code.should.equal('InvalidAssociationID.NotFound')
+    cm.exception.status.should.equal(400)
+    cm.exception.request_id.should_not.be.none
+
+    # Error: Replace association with invalid route table ID
+    with assert_raises(EC2ResponseError) as cm:
+        conn.replace_route_table_association_with_assoc(association_id2, "rtb-1234abcd")
+    cm.exception.code.should.equal('InvalidRouteTableID.NotFound')
+    cm.exception.status.should.equal(400)
+    cm.exception.request_id.should_not.be.none
+
+
 @mock_ec2
 def test_routes_additional():
     conn = boto.connect_vpc('the_key', 'the_secret')