Immunotherapy of malignant melanoma with BCG may be divided into two basic groups: 1. treatment of minimum residual disease. 2. direct intralesional application of BCG. In 19 patients with a histologically confirmed malignant melanoma, direct intralesional application of BCG was used to treat relapsing patients. In 10 of the 19 patients (group A) the relapse was confined to the primary region without signs of distant dissemination. In the remaining 9 patients (group B) signs of the lesion were present prior to BCG application. Our clinical and cytological evaluation bore on local reactions, systemic side reactions and response of non-injected lesions. In patients without signs of distant dissemination, local regression, characterized by a flattening and disappearance of lenticular metastases with scar formation, was achieved in 8/10 patients, while in the noninjected lesions, regression was noted in only 4/10 patients. In 4 patients of group A complete remission lasting 4-6 months was achieved. In the group of patients with signs of distant dissemination, local regression was observed in 6/9, while noninjected lesion regressed in only 1/9. Systemic response to BCG was characterized by febrile reactions with, in the majority of the patients, nausea till vomiting, muscular pain, pain of joints. In the majority of the patients the reaction passed away within 24 hr. A pretreatment with antipyretic and antihistaminic drugs proved of great help. The effect of BCG on the subsequent fate and survival of the patients is not discussed.