Hirudotherapy or leech therapy is a practice that dates back to the ancient ages, where it was employed as an alternative to phlebotomy. However, it has now made a space for itself in today’s modern world therapy after the discovery of several medicinal substances in its saliva which have anti-inflammatory, analgesic, antiseptic, anti-metastatic, anaesthetic, anti-coagulant properties and several other effects. Although the procedure is not risk free, no serious outcomes have been reported in studies till date. Now, scientists are on the verge of developing a mechanical device, which could act as a leech. This review article on leech therapy covers 100 references spanning from 1854-2014 AD and was compiled after scanning all major scientific search engines and also in the classical textbooks of Unani medicine.