Acidic and basic fibroblast growth factor were purified from fresh bovine brain by a combination of differential salt precipitation,ion exchange chromatography and heparin-Sepharose affinity chromatography.Both factors can effectively stimulate the incorporation of ³H-TdR into DNA of 3T3 cell. The apparent molecular masses of aFGF is 13.2 kD and bFGF 15.2—15.8kD.The aFGF has an isoelectric point range of 5.0—6.0 and the amino acid composition consistent with that of standard aFGF.