diff --git a/src/main/java/dev/braintrust/eval/Eval.java b/src/main/java/dev/braintrust/eval/Eval.java
index 64fc7bc..c12de92 100644
--- a/src/main/java/dev/braintrust/eval/Eval.java
+++ b/src/main/java/dev/braintrust/eval/Eval.java
@@ -99,6 +99,10 @@ private void evalOne(String experimentId, DatasetCase<INPUT, OUTPUT> datasetCase
             rootSpan.setAttribute(
                     AttributeKey.stringArrayKey("braintrust.tags"), datasetCase.tags());
         }
+        if (!datasetCase.metadata().isEmpty()) {
+            rootSpan.setAttribute(
+                    AttributeKey.stringKey("braintrust.metadata"), toJson(datasetCase.metadata()));
+        }
         try (var rootScope = BraintrustContext.ofExperiment(experimentId, rootSpan).makeCurrent()) {
             final TaskResult<INPUT, OUTPUT> taskResult;
             { // run task
diff --git a/src/test/java/dev/braintrust/eval/EvalTest.java b/src/test/java/dev/braintrust/eval/EvalTest.java
index 29687ab..75bc419 100644
--- a/src/test/java/dev/braintrust/eval/EvalTest.java
+++ b/src/test/java/dev/braintrust/eval/EvalTest.java
@@ -204,6 +204,35 @@ public List<Score> score(
                 assertTrue(
                         tags.contains("sweet") || tags.contains("savory"),
                         "tags should contain taste");
+                var metadata =
+                        span.getAttributes().get(AttributeKey.stringKey("braintrust.metadata"));
+                assertNotNull(metadata, "root span should have metadata");
+
+                // Parse metadata JSON and verify values based on which case this is
+                @SuppressWarnings("unchecked")
+                Map<String, Object> metadataMap = fromJson(metadata, Map.class);
+                assertNotNull(metadataMap, "metadata should parse as a map");
+                assertTrue(metadataMap.containsKey("calories"), "metadata should contain calories");
+                assertTrue(metadataMap.containsKey("season"), "metadata should contain season");
+
+                if (tags.contains("red")) {
+                    // strawberry case
+                    assertEquals(
+                            32, metadataMap.get("calories"), "strawberry should have 32 calories");
+                    assertEquals(
+                            "summer",
+                            metadataMap.get("season"),
+                            "strawberry should be summer season");
+                } else {
+                    // asparagus case
+                    assertEquals(
+                            20, metadataMap.get("calories"), "asparagus should have 20 calories");
+                    assertEquals(
+                            "spring",
+                            metadataMap.get("season"),
+                            "asparagus should be spring season");
+                }
+
                 numRootSpans.incrementAndGet();
             }
         }