diff --git a/.changeset/anthropic-streaming-cached-input-tokens.md b/.changeset/anthropic-streaming-cached-input-tokens.md
new file mode 100644
index 00000000000..66387941d84
--- /dev/null
+++ b/.changeset/anthropic-streaming-cached-input-tokens.md
@@ -0,0 +1,5 @@
+---
+"@effect/ai-anthropic": patch
+---
+
+populate `cachedInputTokens` in streaming responses from `cache_read_input_tokens`
diff --git a/packages/ai/anthropic/src/AnthropicLanguageModel.ts b/packages/ai/anthropic/src/AnthropicLanguageModel.ts
index c9ee13ba11d..db0025eb391 100644
--- a/packages/ai/anthropic/src/AnthropicLanguageModel.ts
+++ b/packages/ai/anthropic/src/AnthropicLanguageModel.ts
@@ -971,6 +971,7 @@ const makeStreamResponse: (
           case "message_start": {
             // Track usage metadata
             usage.inputTokens = event.message.usage.input_tokens
+            usage.cachedInputTokens = event.message.usage.cache_read_input_tokens ?? undefined
             metaUsage = event.message.usage
 
             // Track response metadata