From November 1976 to March 1979 the Southwest Oncology Group treated 298 patients with limited (disease confined to the chest and encompassed by one radiotherapy port) small-cell carcinoma of the lung with combination chemotherapy and radiotherapy with or without BCG immunotherapy. Two induction chemotherapy programs were utilized: (1) cyclophosphamide, vincristine, methotrexate, fluorouracil; or (2) cyclophosphamide, doxorubicin, and vincristine. Patients received 4500 rads of radiation therapy to the bulk primary tumor and 3000 rads to whole brain followed by maintenance chemotherapy. One-half of all the patients were randomized to receive one vial (5 x 10(8)) of high viability Pasteur BCG by scarification technique given on days 8 and 15 of each 21--28 day treatment cycle. Increased granulocytopenia accompanied the addition of BCG immunotherapy. Patients receiving BCG achieved a response rate of 49% vs. those patients not receiving BCG of 44% (P = 0.579). Median response duration was 40 weeks for the BCG arms and 38 weeks for the arms without BCG; survival was no different, 42 weeks for the BCG arms vs. 50 weeks for the arms without BCG. In patients who responded to therapy and survived longer than one year, those who continued to receive BCG therapy demonstrated a slight, yet significant, survival benefit over those patients not receiving BCG (93 weeks vs. 81 weeks, P = 0.03). It appears that BCG immunotherapy has no beneficial effect on response rate, duration of response, or survival in programs using chemotherapy and radiotherapy for control of limited small-cell carcinoma of the lung except in this small group of long-term survivors.