An immunoperoxidase reaction was used for the titration of immunoglobulins G and M antibodies to BCG in 171 leprosy patients from Dakar. The results show mean titers decreasing from lepromatous to tuberculoid cases. The antibody profiles of some clinical forms such as reverse reactions, erythema nodosum leprosum are discussed. This test associated to the Mitsuda reaction, bacteriology and histology should allow an easier classification of the borderline forms. The main advantages of the technique are simplicity, speed, low cost and the easy availability of the BCG. These qualities are essential in endemic zone.
