Patients with limited-stage small-cell carcinoma of the lung (SCCL) were randomly assigned to a four-drug chemotherapy program consisting of methotrexate, doxorubicin, cyclophosphamide, and CCNU (MACC) or to a regimen consisting of cyclophosphamide, CCNU, and vincristine alternated with Adriamycin (Adria Laboratories, Columbus, Ohio) and vincristine (CCV/AV). All patients received 4,500 cGy, in a split course, to the primary tumor, mediastinum, and supraclavicular lymph node drainage areas and 3,000 cGy to the whole brain. After four cycles of chemotherapy, patients were randomly assigned to chemotherapy plus methanol extractable residue of BCG (MER-BCG) or no MER-BCG. The complete response frequencies were similar for the two regimens (54% and 48%) as were the median survivals (12.0 and 11.5 months) and the two-year survival rates (15% and 17%). Immunotherapy with MER-BCG did not prolong the time to disease progression or improve survival. Women had a greater chance of achieving a complete remission independent of performance status. There was a complex interaction between sex and the chemotherapy regimens that may have important implications for the design and stratification of future trials in SCCL.