The crystal induced chemotactic factor is a protein that is released by neutrophils in response to a phagocytic stimulus like monosodium urate or calcium pyrophosphate crystals. This protein has been postulated to play an important role in the development of crystal-induced arthritis. In this report, we present a protocol for its purification which involved ammonium sulfate fractionation, affinity chromatography, lectin chromatography, and high pressure chromatography (HPLC). The purified protein migrated as a single band on SDS-PAGE. Based on its electrophoretic and chromatographic (HPLC) properties, it appears to have a m.w. of 15,000. It has a blocked N-terminal since our attempt to sequence the chemotactic protein by established procedures failed. The protein contains one methionine residue which appears to be essential for its chemotactic activity since cyanogen bromide treatment abolished its chemotactic activity. To our knowledge this is the first report on purification of this autocrine leukoattractant from human neutrophils.