I had some difficulty stripping all default NS attributes for an ns-uri in one shot, the following will work though...first strip the documentElement namespace, then getElementsByTagNameNS() -- the documentation should reflect that the 2nd argument is actually the name of the tag, not the local namespace prefix as I first expected:<?phpfunction strip_default_ns( $xml = null, $ns_uri = 'http://example.com/XML-Foo' ) { $ns_local = ''; $ns_tag = '*'; if ( empty($xml) ) return false; //remove document namespace $dom = new DOMDocument(); $dom->loadXML($xml); $dom->documentElement->removeAttributeNS($ns_uri, $ns_local); //strip element namespaces foreach ( $dom->getElementsByTagNameNS($ns_uri, $ns_tag) as $elem ) { $elem->removeAttributeNS($ns_uri, $ns_local); } return $dom->saveXML();}$stripped_xml = strip_default_ns($the_xml);?>$stripped_xml can now take advantage of running XPath queries on it for the NULL namespace.