Before discussing the establishment and functioning of the first real leprosarium in Iran, a brief explanation is given of the pathology of leprosy, the various names are listed under which it was known in Persian, and the earliest archeological evidence of its occurrence is presented. Also, societal behavior in Imperial Iran towards lepers is highlighted, while reference is made to the earliest medical descriptions of leprosy in Persian. Little is known about the occurrence of leprosy in Iran over the centuries, as evidenced by the lack of knowledge about its prevalence among medical practitioners and institutions in Iran, even as late as the 1920s. Although segregated villages with lepers existed prior to 1926, it was only as of then that the Mehrab Khan village became the first true Iranian leprosarium, when regular institutional medical treatment was offered by American missionary physicians. The funding agencies, medical personnel and treatment, the living environment of lepers and their numbers in Mehrab Khan are discussed as well as how its population size and status changed over time, and how it was transformed into a structural component of public medical care. Finally and briefly, the establishment and functioning of two other Iranian leprosaria is discussed as well as the slow but sure disappearance of the disease in Iran.