The results of treatment of the group of leprosy patients at the lepromatous side of the leprosy spectrum registered at the Department of Dermatology of the University of Amsterdam in the years 1950–1976 were studied. The average duration of treatment to obtain bacteriologically negative skin biopsies in patients who were untreated at the time of registration, was 5 years. A substantial number of patients suffered a relapse; the main reasons for these relapses were discontinuation of treatment and DDS treatment in low dosag