Abstract Medicinal leech therapy has been used for centuries. Its popularity reached its peak in the early part of the 19th century and then plummeted for about a century only to resurge after the mid-20th century. Leeches feed on blood by anchoring themselves on the skin of vertebrates and in the process inject saliva into the host. Leech saliva contains more than 100 bioactive molecules of which more than 20 have been identified with useful healing properties. It has antithrombin, antiplatelet, analgesic, anti-inflammatory, antimicrobial, vasodilatory and other properties that are beneficial in the treatment of cardiovascular diseases, arthritis, carcinomas, diabetes mellitus. Leech therapy is used by plastic and reconstructive surgeons for replantation of digits, salvage of failing flaps etc. Leech therapy has a huge potential for future therapeutics.