Basic Fibroblast Growth Factor (FGF) is substantially purified by the employment of affinity chromatography using heparin-linked support material. Described is a simplified three step procedure for extracting basic FGF from either mammalian brain or mammalian pituitary tissue. Salt precipitation, e.g., with ammonium sulfate is used to provide a partially purified precipitate that is then subjected to ion-exchange chromatography, e.g., using a Carboxymethyl-Sephadex column. Substantially pure basic FGF fractions are then obtained by fractionating the further partially purified fractions using affinity chromatography on a heparin-linked support e.g., Heparin-Sepharose.