diff --git a/dev/restate/service/protocol.proto b/dev/restate/service/protocol.proto
index 9e68455..a2ce02e 100644
--- a/dev/restate/service/protocol.proto
+++ b/dev/restate/service/protocol.proto
@@ -157,6 +157,20 @@ message ClearStateEntryMessage {
 message ClearAllStateEntryMessage {
 }
 
+// Completable: Yes
+// Fallible: No
+// Type: 0x0800 + 4
+message GetStateKeysEntryMessage {
+  message StateKeys {
+    repeated bytes keys = 1;
+  }
+
+  oneof result {
+    StateKeys value = 14;
+    Failure failure = 15;
+  };
+}
+
 // ------ Syscalls ------
 
 // Completable: Yes
diff --git a/service-invocation-protocol.md b/service-invocation-protocol.md
index 16b7715..d592ad0 100644
--- a/service-invocation-protocol.md
+++ b/service-invocation-protocol.md
@@ -284,6 +284,7 @@ descriptions in [`protocol.proto`](dev/restate/service/protocol.proto).
 | ------------------------------- | -------- | ----------- | -------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------- |
 | `PollInputStreamEntryMessage`   | `0x0400` | Yes         | No       | Carries the invocation input message(s) of the invocation. Note: currently the runtime always sends this entry completed, but this may change in future.         |
 | `GetStateEntryMessage`          | `0x0800` | Yes         | No       | Get the value of a service instance state key.                                                                                                                   |
+| `GetStateKeysEntryMessage`      | `0x0804` | Yes         | No       | Get all the known state keys for this service instance. Note: the completion value for this message is a protobuf of type `GetStateKeysEntryMessage.StateKeys`.  |
 | `SleepEntryMessage`             | `0x0C00` | Yes         | No       | Initiate a timer that completes after the given time.                                                                                                            |
 | `InvokeEntryMessage`            | `0x0C01` | Yes         | Yes      | Invoke another Restate service.                                                                                                                                  |
 | `AwakeableEntryMessage`         | `0x0C03` | Yes         | No       | Arbitrary result container which can be completed from another service, given a specific id. See [Awakeable identifier](#awakeable-identifier) for more details. |