The common river leech is commonly found in the South East Asia region. The researchers conducted a study in which they aim to prove the potential anticoagulative property of the common river leech (Hirudinaria sp.). The experiment was done through manual extraction of the leech saliva. The leech saliva and whole blood was used in this experiment. The researchers used five different volumes as to determine the effectiveness of the anticoagulant property of hirudin. Results indicate that their saliva contains a special substance called hirudin which has an anticoagulative property.