diff --git a/Changelog.md b/Changelog.md
index d67c35b..482c670 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -1,5 +1,11 @@
 # Changelog
 
+## 5.0.0
+
+- Added `num_tokens_prompt_total` and `num_tokens_generated` to `CompletionResponse`. This is a
+  breaking change as these were introduced as mandatory parameters rather than optional ones.
+  HTTP API version 1.14.0 or higher is required.
+
 ## 4.1.0
 
 - Added `verify_ssl` flag so you can disable SSL checking for your sessions.
diff --git a/aleph_alpha_client/completion.py b/aleph_alpha_client/completion.py
index ac48523..128d003 100644
--- a/aleph_alpha_client/completion.py
+++ b/aleph_alpha_client/completion.py
@@ -247,8 +247,31 @@ def _asdict(self) -> Mapping[str, Any]:
 
 @dataclass(frozen=True)
 class CompletionResponse:
+    """
+    Describes a completion response
+
+    Parameters:
+        model_version:
+            Model name and version (if any) of the used model for inference.
+        completions:
+            List of completions; may contain only one entry if no more are requested (see parameter n).
+        num_tokens_prompt_total:
+            Number of tokens combined across all completion tasks.
+            In particular, if you set best_of or n to a number larger than 1 then we report the
+            combined prompt token count for all best_of or n tasks.
+        num_tokens_generated:
+            Number of tokens combined across all completion tasks.
+            If multiple completions are returned or best_of is set to a value greater than 1 then
+            this value contains the combined generated token count.
+        optimized_prompt:
+            Describes prompt after optimizations. This field is only returned if the flag
+            `disable_optimizations` flag is not set and the prompt has actually changed.
+    """
+
     model_version: str
     completions: Sequence[CompletionResult]
+    num_tokens_prompt_total: int
+    num_tokens_generated: int
     optimized_prompt: Optional[Prompt] = None
 
     @staticmethod
@@ -259,6 +282,8 @@ def from_json(json: Dict[str, Any]) -> "CompletionResponse":
             completions=[
                 CompletionResult.from_json(item) for item in json["completions"]
             ],
+            num_tokens_prompt_total=json["num_tokens_prompt_total"],
+            num_tokens_generated=json["num_tokens_generated"],
             optimized_prompt=Prompt.from_json(optimized_prompt_json)
             if optimized_prompt_json
             else None,
diff --git a/aleph_alpha_client/version.py b/aleph_alpha_client/version.py
index 7039708..ba7be38 100644
--- a/aleph_alpha_client/version.py
+++ b/aleph_alpha_client/version.py
@@ -1 +1 @@
-__version__ = "4.1.0"
+__version__ = "5.0.0"
diff --git a/tests/test_clients.py b/tests/test_clients.py
index 3327510..10da424 100644
--- a/tests/test_clients.py
+++ b/tests/test_clients.py
@@ -33,7 +33,9 @@ def test_nice_flag_on_client(httpserver: HTTPServer):
     ).respond_with_json(
         CompletionResponse(
             "model_version",
-            [CompletionResult(log_probs=[], completion="foo")],
+            [CompletionResult(log_probs=[], completion="foo", )],
+            num_tokens_prompt_total=2,
+            num_tokens_generated=1,
         ).to_json()
     )
 
@@ -47,11 +49,14 @@ async def test_nice_flag_on_async_client(httpserver: HTTPServer):
     httpserver.expect_request("/version").respond_with_data("OK")
 
     httpserver.expect_request(
-        "/complete", query_string={"nice": "true"}
+        "/complete",
+        query_string={"nice": "true"},
     ).respond_with_json(
         CompletionResponse(
             "model_version",
             [CompletionResult(log_probs=[], completion="foo")],
+            num_tokens_prompt_total=2,
+            num_tokens_generated=1,
         ).to_json()
     )
 
diff --git a/tests/test_complete.py b/tests/test_complete.py
index 863a9fe..a248ced 100644
--- a/tests/test_complete.py
+++ b/tests/test_complete.py
@@ -127,3 +127,34 @@ def test_complete_with_echo(sync_client: Client, model_name: str, prompt_image:
     assert len(completion_result.completion_tokens) > 0
     assert completion_result.log_probs is not None
     assert len(completion_result.log_probs) > 0
+
+@pytest.mark.system_test
+def test_num_tokens_prompt_total_with_best_of(sync_client: Client, model_name: str):
+    tokens = [49222, 2998] # Hello world
+    best_of = 2
+    request = CompletionRequest(
+        prompt = Prompt.from_tokens(tokens),
+        best_of = best_of,
+        maximum_tokens = 1,
+    )
+
+    response = sync_client.complete(request, model=model_name)
+    assert response.num_tokens_prompt_total == len(tokens) * best_of
+
+@pytest.mark.system_test
+def test_num_tokens_generated_with_best_of(sync_client: Client, model_name: str):
+    hello_world = [49222, 2998] # Hello world
+    best_of = 2
+    request = CompletionRequest(
+        prompt = Prompt.from_tokens(hello_world),
+        best_of = best_of,
+        maximum_tokens = 1,
+        tokens = True,
+    )
+
+    response = sync_client.complete(request, model=model_name)
+    completion_result = response.completions[0]
+    assert completion_result.completion_tokens is not None
+    number_tokens_completion = len(completion_result.completion_tokens)
+
+    assert response.num_tokens_generated == best_of * number_tokens_completion
\ No newline at end of file
diff --git a/tests/test_error_handling.py b/tests/test_error_handling.py
index 834d204..485f27e 100644
--- a/tests/test_error_handling.py
+++ b/tests/test_error_handling.py
@@ -111,8 +111,7 @@ def expect_retryable_error(
 
 def expect_valid_completion(httpserver: HTTPServer) -> None:
     httpserver.expect_ordered_request("/complete").respond_with_json(
-        {"model_version": "1", "completions": []}
-    )
+        {"model_version": "1", "completions": [], "num_tokens_prompt_total": 0, "num_tokens_generated": 0})
 
 
 def expect_valid_version(httpserver: HTTPServer) -> None: