Abstract: A new fibrinogenase (EC 3.4.21.5) was isolated and purified from the venom of Chinese habu snake (Trimeresurus mucrosquamatus) by DEAE-SephadexA-50,DEAE-Sepharose CL-6B,MonoQ (FPLC) cclumn chromatography.It showed a single protein band both in sodium dodecyl sulfate (SDS)-polyacrylamide gel egectrophoresis and alkaline polyacrylamide gel electrophoresis.The molecular weight was estimated to be 26000 by SDS-polyacrylamide gel electrophoresis.The isoelectric point was found to be Ph 4.7.It was a glycoprotein containing 6.4% carbohydrate with 0.3% neutral sugar,1.2% sialic acid,4.9% hexosamine.It was composed of about 178 amino acid residues and rich in glycine and aspartic acid.The fibrinogenase of the venom of T.mucrosquamatus TWVFg was heat stable but labile to acid.Its extinction coefficient (1 mg/ml) at 280 nm was 1.558.Purified TMVFg had strong arginine esterase activity;the Km to benzoylarginiue ethylester (BAEE) was 1.4×10-3M.The enzyme activity could be inhibited by pheny.Imethanesulfonyfluoride (PMSF);but was not affected by ethylenediamine tetraacetic acid (EDTA).TMVFg had fibrinogenolytic activity;electrophoresis of fibrinogen degraded with TMVFg revealed the rapid disappearance of the α (alpha) and β (beta)-chains and the appearance of lower molecular weight frag ments.TMVFg did not cause fibrinogen solution clotting,nor coagulating plasma and showed neither hemorrhagic activity nor proteolytic activity toward casein.TMVFg had activating fibrinolytic activity.