XPath [16] was introduced by the W3C as a standard language for specifying node selection, matching conditions, and for computing values from an XML document. XPath is now used in many XML standards such as XSLT [15] or the forthcoming XQuery [14] database access language. Since efficient XML content querying is crucial for the performance of almost all XML processing architectures, a growing need for studying high performance XPath-based querying has emerged. Our approach aims at optimizing XPath performance through static analysis and syntactic transformation of XPath expressions.