diff --git a/src/components/script/dom/bindings/codegen/Bindings.conf b/src/components/script/dom/bindings/codegen/Bindings.conf
index 36dbf48a6e8..ffa19b30198 100644
--- a/src/components/script/dom/bindings/codegen/Bindings.conf
+++ b/src/components/script/dom/bindings/codegen/Bindings.conf
@@ -33,6 +33,7 @@ DOMInterfaces = {
         'createProcessingInstruction',
         'createTextNode',
         'getElementsByTagName',
+        'getElementsByTagNameNS',
         'title',
     ],
 },
@@ -45,6 +46,7 @@ DOMInterfaces = {
         'getBoundingClientRect',
         'getClientRects',
         'getElementsByTagName',
+        'getElementsByTagNameNS',
         'id',
         'innerHTML',
         'outerHTML',
diff --git a/src/components/script/dom/document.rs b/src/components/script/dom/document.rs
index 9190e36b0dd..fba0d4b506f 100644
--- a/src/components/script/dom/document.rs
+++ b/src/components/script/dom/document.rs
@@ -35,7 +35,7 @@ use dom::window::Window;
 use html::hubbub_html_parser::build_element_from_tag;
 use hubbub::hubbub::{QuirksMode, NoQuirks, LimitedQuirks, FullQuirks};
 use layout_interface::{DocumentDamageLevel, ContentChangedDocumentDamage};
-use servo_util::namespace::Null;
+use servo_util::namespace::{Namespace, Null};
 use servo_util::str::DOMString;
 
 use extra::url::{Url, from_str};
@@ -216,6 +216,15 @@ impl Document {
         HTMLCollection::by_tag_name(&self.window, &NodeCast::from(abstract_self), tag_name)
     }
 
+    // http://dom.spec.whatwg.org/#dom-document-getelementsbytagnamens
+    pub fn GetElementsByTagNameNS(&self, abstract_self: &JS<Document>, maybe_ns: Option<DOMString>, tag_name: DOMString) -> JS<HTMLCollection> {
+        let namespace = match maybe_ns {
+            Some(namespace) => Namespace::from_str(namespace),
+            None => Null
+        };
+        HTMLCollection::by_tag_name_ns(&self.window, &NodeCast::from(abstract_self), tag_name, namespace)
+    }
+
     // http://dom.spec.whatwg.org/#dom-nonelementparentnode-getelementbyid
     pub fn GetElementById(&self, id: DOMString) -> Option<JS<Element>> {
         // TODO: "in tree order, within the context object's tree"
diff --git a/src/components/script/dom/element.rs b/src/components/script/dom/element.rs
index 108d9aed19e..a004126cc6d 100644
--- a/src/components/script/dom/element.rs
+++ b/src/components/script/dom/element.rs
@@ -509,11 +509,15 @@ impl Element {
         HTMLCollection::by_tag_name(&doc.window, &NodeCast::from(abstract_self), localname)
     }
 
-    // http://dom.spec.whatwg.org/#dom-element-getelementsbytagnamens
-    pub fn GetElementsByTagNameNS(&self, _namespace: Option<DOMString>, _localname: DOMString) -> Fallible<JS<HTMLCollection>> {
-        // FIXME: stub - https://github.com/mozilla/servo/issues/1660
+    pub fn GetElementsByTagNameNS(&self, abstract_self: &JS<Element>, maybe_ns: Option<DOMString>,
+                                  localname: DOMString) -> JS<HTMLCollection> {
         let doc = self.node.owner_doc();
-        Ok(HTMLCollection::new(&doc.get().window, ~[]))
+        let doc = doc.get();
+        let namespace = match maybe_ns {
+            Some(namespace) => Namespace::from_str(namespace),
+            None => Null
+        };
+        HTMLCollection::by_tag_name_ns(&doc.window, &NodeCast::from(abstract_self), localname, namespace)
     }
 
     // http://dom.spec.whatwg.org/#dom-element-getelementsbyclassname
diff --git a/src/components/script/dom/htmlcollection.rs b/src/components/script/dom/htmlcollection.rs
index b2a8ca0aa02..4d18e9734f4 100644
--- a/src/components/script/dom/htmlcollection.rs
+++ b/src/components/script/dom/htmlcollection.rs
@@ -9,6 +9,7 @@ use dom::bindings::utils::{Reflectable, Reflector, reflect_dom_object};
 use dom::element::Element;
 use dom::node::{Node, NodeHelpers};
 use dom::window::Window;
+use servo_util::namespace::Namespace;
 use servo_util::str::DOMString;
 
 #[deriving(Encodable)]
@@ -50,6 +51,10 @@ impl HTMLCollection {
     pub fn by_tag_name(window: &JS<Window>, root: &JS<Node>, tag_name: DOMString) -> JS<HTMLCollection> {
         HTMLCollection::create(window, root, |elem| elem.get().tag_name == tag_name)
     }
+
+    pub fn by_tag_name_ns(window: &JS<Window>, root: &JS<Node>, tag_name: DOMString, namespace: Namespace) -> JS<HTMLCollection> {
+        HTMLCollection::create(window, root, |elem| elem.get().namespace == namespace && elem.get().tag_name == tag_name)
+    }
 }
 
 impl HTMLCollection {
diff --git a/src/components/script/dom/webidls/Document.webidl b/src/components/script/dom/webidls/Document.webidl
index 11e92a0930e..9dc92b1520f 100644
--- a/src/components/script/dom/webidls/Document.webidl
+++ b/src/components/script/dom/webidls/Document.webidl
@@ -21,6 +21,7 @@ interface Document : Node {
   readonly attribute DocumentType? doctype;
   readonly attribute Element? documentElement;
   HTMLCollection getElementsByTagName(DOMString localName);
+  HTMLCollection getElementsByTagNameNS(DOMString? namespace, DOMString localName);
   Element? getElementById(DOMString elementId);
 
   [Creator, Throws]
diff --git a/src/components/script/dom/webidls/Element.webidl b/src/components/script/dom/webidls/Element.webidl
index 6c393f00067..e26c9415d4a 100644
--- a/src/components/script/dom/webidls/Element.webidl
+++ b/src/components/script/dom/webidls/Element.webidl
@@ -51,7 +51,6 @@ interface Element : Node {
   boolean hasAttributeNS(DOMString? namespace, DOMString localName);
 
   HTMLCollection getElementsByTagName(DOMString localName);
-  [Throws]
   HTMLCollection getElementsByTagNameNS(DOMString? namespace, DOMString localName);
   HTMLCollection getElementsByClassName(DOMString classNames);
 };