Purification of HBGFs from bovine brain through three steps: 40 to 80% saturated ammonium sulfate fractionatton of bovine brain extract, CM-Sephadex C-50 ionexchange chromatographe, and heparin affinity chromatography. SDS-PAGE revealed the presence of a single band a with molecular weights about 16 kilodalton. The ability of HBGFs to stimulate cell proliferation in vitro was studied using human umbilical vein EC as target cells. The result showed that when HBGFs was added to the cultures, EC could be made to long-term serial cultivation, and resuscitated successfully after freezing and the serum requirement for EC growth could be reduced.