A thrombin-like enzyme, balterobin, was purified from the venom of Bothrops alternatus. The purification steps included Sephadex G-75, heparin-sepharose and reverse phase HPLC C-18 column. Balterobin showed an apparent molecular weight of 30,000 in non-reduced conditions and displays a specific coagulant activity of 32.8 NIH units/mg over bovine fibrinogen. It also exhibits arginine amidase activity on DL-BAPNA. Like thrombin-like enzymes from other snakes, balterobin possesses valine as N-terminal residue, and is inhibited by PMSF.361059-63