diff --git a/src/core/__tests__/jsxns-test.js b/src/core/__tests__/jsxns-test.js
new file mode 100644
index 0000000000000..c362ddf33fb03
--- /dev/null
+++ b/src/core/__tests__/jsxns-test.js
@@ -0,0 +1,89 @@
+/**
+ * Copyright 2013-2014 Facebook, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * @jsx React.DOM
+ * @jsxns {"MyNamespace":"SampleNamespace"}
+ * @emails react-core
+ */
+
+"use strict";
+
+var React = require('React');
+var ReactTestUtils = require('ReactTestUtils');
+
+var reactComponentExpect= require('reactComponentExpect');
+
+var SampleNamespace = {
+  ComponentA: React.createClass({
+    render: function() {
+      return (
+        <MyNamespace:ComponentB ref="childComponent">
+          <p>Test</p>
+        </MyNamespace:ComponentB>
+      );
+    }
+  }),
+
+  ComponentB: React.createClass({
+    render: function() {
+      return (
+        <div className="wrapper">
+          {this.props.children}
+        </div>
+      );
+    }
+  })
+};
+
+var renderJSXNSComponent = function() {
+  var testJSXNSComponent =
+      ReactTestUtils.renderIntoDocument(<MyNamespace:ComponentA />);
+
+  reactComponentExpect(testJSXNSComponent)
+      .toBeCompositeComponentWithType(SampleNamespace.ComponentA);
+
+  var generalContainer = testJSXNSComponent.refs.childComponent;
+
+  reactComponentExpect(generalContainer)
+      .toBeCompositeComponentWithType(SampleNamespace.ComponentB);
+
+  return testJSXNSComponent;
+};
+
+describe('jsxns', function() {
+  beforeEach(function() {
+    require('mock-modules').dumpCache();
+  });
+
+  /**
+   * Ensure that component respects namespace correctly.
+   */
+  it("Should render namespaced components correctly", function() {
+    var testJSXNSComponent = renderJSXNSComponent();
+
+    var child = ReactTestUtils.findRenderedDOMComponentWithClass(testJSXNSComponent, 'wrapper');
+
+    expect(child).toBeDefined();
+  });
+
+  /**
+   * Fails for undefined namespaces.
+   */
+   it("Should fail for undefined namespace", function() {
+    expect(function() {
+      ReactTestUtils.renderIntoDocument(<MyNamespace:ComponentC />);
+    }).toThrow();
+   });
+});
diff --git a/vendor/fbtransform/transforms/react.js b/vendor/fbtransform/transforms/react.js
index 2e50fb9b33108..85850016eac95 100644
--- a/vendor/fbtransform/transforms/react.js
+++ b/vendor/fbtransform/transforms/react.js
@@ -47,22 +47,54 @@ var JSX_ATTRIBUTE_TRANSFORMS = {
   }
 };
 
-function visitReactTag(traverse, object, path, state) {
+function loadJSXNamespaces(state) {
+  var namespaces = {};
+  var jsxns = utils.getDocblock(state).jsxns;
+
+  if (jsxns) {
+    try {
+      namespaces = JSON.parse(jsxns);
+    } catch (e) {
+      throw new SyntaxError('Error parsing @jsxns docblock: ' + e.message);
+    }
+  }
+
+  return namespaces;
+}
+
+function normalizeTag(nameObject, state) {
   var jsxObjIdent = utils.getDocblock(state).jsx;
+  var jsxNamespaces = loadJSXNamespaces(state);
+  var isFallbackTag = FALLBACK_TAGS.hasOwnProperty(nameObject.name);
+  var namespace = nameObject.namespace;
+
+  if (isFallbackTag) {
+    namespace = jsxObjIdent;
+  } else if (jsxNamespaces.hasOwnProperty(namespace)) {
+    namespace = jsxNamespaces[namespace];
+  } else if (namespace) {
+    throw new Error(
+       'Undefined namespace used on tag: ' + namespace + ':' + nameObject.name
+       + '. Define any custom namespaces with @jsxns.');
+  }
+
+  if (namespace) {
+    return namespace + '.' + nameObject.name;
+  } else {
+    return nameObject.name;
+  }
+}
+
+function visitReactTag(traverse, object, path, state) {
   var openingElement = object.openingElement;
   var nameObject = openingElement.name;
   var attributesObject = openingElement.attributes;
+  var tagIdentifier = normalizeTag(nameObject, state);
 
   utils.catchup(openingElement.range[0], state);
 
-  if (nameObject.namespace) {
-    throw new Error(
-       'Namespace tags are not supported. ReactJSX is not XML.');
-  }
-
-  var isFallbackTag = FALLBACK_TAGS.hasOwnProperty(nameObject.name);
   utils.append(
-    (isFallbackTag ? jsxObjIdent + '.' : '') + (nameObject.name) + '(',
+    tagIdentifier + '(',
     state
   );