Snake venom proteases are useful tools for studying coagulation reactions. Venoms contain more than 20 different compounds, mostly proteins and polypeptides. Some of the proteins in snake venom have very specific effects on various biological functions including blood coagulation, blood pressure regulation, transmission of the nervous or muscular impulse and have been developed for use as diagnostic tools. Plasma coagulation Factors are usually inactive and require proteolytic activation as a first step towards a chronometric or colorimetric assay. It is often advantageous to use specific enzymes from snake venoms to activate coagulation Factors rather than physiological activators. In contrast to other activators, many snake venom enzymes are not dependent from cofactors, phospholipid or calcium ions.