Abstract. Often, XML documents stored in an XML database must be transformed by an XSL processor into a client-specific format before queries are submitted. In applications where XML documents are large and the query result is relatively small, it is of considerable advantage to retrieve and process only that part of the document, which is used by the query. Our contribution transforms an XPath query defined over the client’s XML format into a query over the format used by the database, such that the evaluation of the latter query returns a reduced document containing only as much data as is needed to evaluate the original query.