Abstract: A process for extracting and isolating from snake venoms the enzymatic component having "in vitro" coagulant activity and "in vivo" anticoagulant activity from the other components having "in vitro" coagulant activity and from the protein components, wherein the snake venom, dissolved in a medium suitable for chromatographic separation treatment is passed through a column filled with a solid support for selective absorption of said in vivo anticoagulant enzyme, not soluble in aqueous solvents, bound to a substratum or inhibitor of said enzyme, a first elution medium at pH 6-7 and molarity less than or equal to 0.05M is passed through said filling, wherein said venom has been introduced, the eluate is collected in subsequent portions until the elution of more than 95% of the protein components of the venom and an "in vitro" coagulant fraction, different from that present in the second eluate are obtained, a second elution medium at a pH even greater than 9 and molarity greater than or equal to 0.