A series of forty-five cases of chancroid was observed between September 1937 and July 1938. A diagnosis was established by clinical signs, positive smears for Ducrey bacilli stained with methylene green pyronine (Una Pappenheim), a positive skin test with Ducrey antigen and negative blood Wassermann test, dark field examinations and Frei test. The lesions ranged from dime-sized (18 mm.) ulcerations on the prepuce to complete sloughing of the glans penis. The average duration, prior to treatment, was from four weeks to two years. Preliminary treatment with soap and water for a period of one week was instituted and, if no results were obtained, sulfanilamide was then given. Treatment with sulfanilamide consisted of the administration of 80 grains (5.2 Gm.) of the drug in divided doses for the first five days and 40 grains (2.6 Gm.) in divided doses for nine additional days. It was found that without exception the treated