From ancient time leprosy has been regarded as a terrifying, stigmatized disease; nevertheless, its cause remained unidentified up to the late 19th century. For centuries numerous leprosy victims worldwide suffered from its morbidity and were socially isolated. The afflicted individuals were segregated because they were considered 'unclean' and had to live in leper colonies, generally under very poor conditions. Physicians believed that leprosy was an incurable, highly contagious, and hereditary disease. In 1873 the Norwegian physician, Gerhard Armauer Hansen (1841-1912), ended the myth of leprosy and discovered its causative agent, known as Mycobacterium leprae. Hansen's discovery was a great triumph in the fight against leprosy. In the 1930's, the first effective antileprosy drug, dapsone, was introduced and in the early 1980's multi-drug therapy was popularized because of high efficacy in resistant cases. Here, we have presented a brief look at the history of leprosy in the world with special focus on the historical account of leprosy in Iran, particularly during the 19th and 20th centuries.