A new method for extraction and analysis of acetone in human urine based on headspace solid phase microextraction using a mixture of activated carbon and zeolite as sorbents in a PVC matrix coated on a silver wire is described. Unlike commercial fibers, which are coated on fused silica, the proposed coating adheres strongly to the silver wire and is thermally stable up to 250oC. After optimization of coating composition and microextraction conditions the fiber was used for the analysis of acetone in human urine. As a Biomedical application, determination of ketone bodies (b-hydroxybutyrate and acetoacetate) by chemical conversion of them to acetone followed by solid phase microextraction and gas chromatographic determination are presented.