AIM: To determine the role of chemokine and its receptors in the pathogenesis of ankylosing spondylitis (AS). METHODS: Gene expression profiles of peripheral blood mononuclea r cells (PBMC) in 13 AS patients and 7 healthy volunteers were determined by cDN A microarray with 588 targeting gene filter. Differentiated expressed CXCR4 and its only ligand SDF-1 were confirmed by semi-quantitative RT-PCR, ELISA, immunoh istochemistry and FACS analysis using PBMC, synovial fluid mononuclear cells (SF MC) and synoviocytes. RESULTS: The gene expression profile of AS patients was signific antly different from those of healthy volunteers. Higher expression of CXCR4 in monocytes and CD8+ T lymphocytes from PBMC in AS patients were found with st atis tical significance (P