diff --git a/scripts/fiber/tests-passing.txt b/scripts/fiber/tests-passing.txt
index fb94519a931b6..e5fd7165a90f0 100644
--- a/scripts/fiber/tests-passing.txt
+++ b/scripts/fiber/tests-passing.txt
@@ -1972,6 +1972,9 @@ src/renderers/dom/test/__tests__/ReactTestUtils-test.js
 * should enable rendering of cloned element
 * should set the type of the event
 * should work with renderIntoDocument
+* should log a deprecation warning if ReactTestUtils.isCompositeComponentElement is invoked
+* should log a deprecation warning if ReactTestUtils.isCompositeComponentElementWithType is invoked
+* should log a deprecation warning if ReactTestUtils.getRenderedChildOfCompositeComponent is invoked
 
 src/renderers/native/__tests__/ReactNativeAttributePayload-test.js
 * should work with simple example
diff --git a/src/renderers/dom/test/ReactTestUtilsEntry.js b/src/renderers/dom/test/ReactTestUtilsEntry.js
index a08eef557cb88..0f04b0baf876a 100644
--- a/src/renderers/dom/test/ReactTestUtilsEntry.js
+++ b/src/renderers/dom/test/ReactTestUtilsEntry.js
@@ -19,6 +19,7 @@ var ReactInstanceMap = require('ReactInstanceMap');
 var ReactShallowRenderer = require('ReactShallowRendererEntry'); // TODO (bvaughn) Remove this import before 16.0.0
 var ReactTypeOfWork = require('ReactTypeOfWork');
 var SyntheticEvent = require('SyntheticEvent');
+var lowPriorityWarning = require('lowPriorityWarning');
 
 var invariant = require('fbjs/lib/invariant');
 var warning = require('fbjs/lib/warning');
@@ -194,7 +195,6 @@ var ReactTestUtils = {
     return constructor === type;
   },
 
-  // TODO: deprecate? It's undocumented and unused.
   isCompositeComponentElement: function(inst) {
     if (!React.isValidElement(inst)) {
       return false;
@@ -208,7 +208,6 @@ var ReactTestUtils = {
     );
   },
 
-  // TODO: deprecate? It's undocumented and unused.
   isCompositeComponentElementWithType: function(inst, type) {
     var internalInstance = ReactInstanceMap.get(inst);
     var constructor = internalInstance._currentElement.type;
@@ -217,7 +216,6 @@ var ReactTestUtils = {
       constructor === type);
   },
 
-  // TODO: deprecate? It's undocumented and unused.
   getRenderedChildOfCompositeComponent: function(inst) {
     if (!ReactTestUtils.isCompositeComponent(inst)) {
       return null;
@@ -570,4 +568,19 @@ Object.keys(topLevelTypes).forEach(function(eventType) {
   );
 });
 
+[
+  'isCompositeComponentElement',
+  'isCompositeComponentElementWithType',
+  'getRenderedChildOfCompositeComponent',
+].forEach(fnName => {
+  var fn = ReactTestUtils[fnName];
+  ReactTestUtils[fnName] = function(...args) {
+    lowPriorityWarning(
+      false,
+      `ReactTestUtils.${fnName} is deprecated as of React v15.6.2.`,
+    );
+    return fn(...args);
+  };
+});
+
 module.exports = ReactTestUtils;
diff --git a/src/renderers/dom/test/__tests__/ReactTestUtils-test.js b/src/renderers/dom/test/__tests__/ReactTestUtils-test.js
index 624bc9c9fed7a..f2548848ba8c5 100644
--- a/src/renderers/dom/test/__tests__/ReactTestUtils-test.js
+++ b/src/renderers/dom/test/__tests__/ReactTestUtils-test.js
@@ -843,5 +843,26 @@ describe('ReactTestUtils', () => {
         jasmine.objectContaining({target: input}),
       );
     });
+
+    [
+      'isCompositeComponentElement',
+      'isCompositeComponentElementWithType',
+      'getRenderedChildOfCompositeComponent',
+    ].forEach(fnName => {
+      it(
+        `should log a deprecation warning if ReactTestUtils.${fnName} is invoked`,
+        () => {
+          spyOn(console, 'warn');
+
+          try {
+            ReactTestUtils[fnName]();
+          } catch (_) {}
+
+          expect(console.warn.calls.argsFor(0)[0]).toBe(
+            `Warning: ReactTestUtils.${fnName} is deprecated as of React v15.6.2.`,
+          );
+        },
+      );
+    });
   });
 });