%LibXML% supports DTD, Schema and RelaxNG validation, during parsing, and post parsing. boolean attribute DOMDocument->validateOnParse boolean DOMDocument->validate(string filename) boolean DOMDocument->schemaValidate(string filename) boolean DOMDocument->relaxNGValidate(string filename) validateOnParse = true; $dom->load('note-invalid.xml'); ?>]]> load('note.xml'); if (!$dom->validate('note.dtd')) { print "Document note.dtd is not valid\n"; } else { print "Document note.dtd is valid\n"; } ?>]]>