diff --git a/rclpy/rclpy/parameter_service.py b/rclpy/rclpy/parameter_service.py
index 70830facf..6a8803fef 100644
--- a/rclpy/rclpy/parameter_service.py
+++ b/rclpy/rclpy/parameter_service.py
@@ -12,6 +12,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+
+from typing import TYPE_CHECKING
 import weakref
 
 from rcl_interfaces.msg import ListParametersResult
@@ -23,10 +25,13 @@
 from rclpy.qos import qos_profile_parameters
 from rclpy.validate_topic_name import TOPIC_SEPARATOR_STRING
 
+if TYPE_CHECKING:
+    from rclpy.node import Node
+
 
 class ParameterService:
 
-    def __init__(self, node):
+    def __init__(self, node: 'Node'):
         self._node_weak_ref = weakref.ref(node)
         nodename = node.get_name()
 
@@ -65,7 +70,11 @@ def __init__(self, node):
             qos_profile=qos_profile_parameters
         )
 
-    def _describe_parameters_callback(self, request, response):
+    def _describe_parameters_callback(
+        self,
+        request: DescribeParameters.Request,
+        response: DescribeParameters.Response
+    ) -> DescribeParameters.Response:
         node = self._get_node()
         for name in request.names:
             try:
@@ -76,7 +85,11 @@ def _describe_parameters_callback(self, request, response):
             response.descriptors.append(descriptor)
         return response
 
-    def _get_parameters_callback(self, request, response):
+    def _get_parameters_callback(
+        self,
+        request: GetParameters.Request,
+        response: GetParameters.Response
+    ) -> GetParameters.Response:
         node = self._get_node()
         for name in request.names:
             try:
@@ -87,7 +100,11 @@ def _get_parameters_callback(self, request, response):
             response.values.append(param.get_parameter_value())
         return response
 
-    def _get_parameter_types_callback(self, request, response):
+    def _get_parameter_types_callback(
+        self,
+        request: GetParameterTypes.Request,
+        response: GetParameterTypes.Response
+    ) -> GetParameterTypes.Response:
         node = self._get_node()
         for name in request.names:
             try:
@@ -98,7 +115,11 @@ def _get_parameter_types_callback(self, request, response):
             response.types.append(value)
         return response
 
-    def _list_parameters_callback(self, request, response):
+    def _list_parameters_callback(
+        self,
+        request: ListParameters.Response,
+        response: ListParameters.Response
+    ) -> ListParameters.Response:
         node = self._get_node()
         try:
             response.result = node.list_parameters(request.prefixes, request.depth)
@@ -106,7 +127,11 @@ def _list_parameters_callback(self, request, response):
             response.result = ListParametersResult()
         return response
 
-    def _set_parameters_callback(self, request, response):
+    def _set_parameters_callback(
+            self,
+            request: SetParameters.Request,
+            response: SetParameters.Response
+            ) -> SetParameters.Response:
         node = self._get_node()
         for p in request.parameters:
             param = Parameter.from_parameter_msg(p)
@@ -120,7 +145,11 @@ def _set_parameters_callback(self, request, response):
             response.results.append(result)
         return response
 
-    def _set_parameters_atomically_callback(self, request, response):
+    def _set_parameters_atomically_callback(
+            self,
+            request: SetParametersAtomically.Request,
+            response: SetParametersAtomically.Response
+            ) -> SetParametersAtomically.Response:
         node = self._get_node()
         try:
             response.result = node.set_parameters_atomically([
@@ -132,7 +161,7 @@ def _set_parameters_atomically_callback(self, request, response):
                 )
         return response
 
-    def _get_node(self):
+    def _get_node(self) -> 'Node':
         node = self._node_weak_ref()
         if node is None:
             raise ReferenceError('Expected valid node weak reference')