Abstract 139 patients with small cell lung cancer were randomized to receive combination chemotherapy (vincristine, cyclophosphamide and doxorubicin) alone or with irradiation to the primary tumour site after three cycles of chemotherapy. In addition, they were randomized to receive either intravenous or intrathecal methotrexate with the first three chemotherapy cycles. Ninety-one patients had limited disease and 48 extensive disease. Thirty-six patients achieved complete response and 57 partial response after completion of protocol treatment for an overall response rate of 67% (95%, CI 58–75%). Seventy-nine (85%) of the responding patients subsequently relapsed. Relapse rates for all responding patients and those achieving complete response were similar whether or not they received radiotherapy. Radiotherapy reduced the local recurrence rate in the chest in all responders ( P=0.018) but this was not significant in the group of complete responders ( P=0.158). The overall median survival was 15 months (95%; C1 13–17%) for those with limited disease and 7 months (95%; CI 4–8%) in those with extensive disease. In patients with limited disease, those treated with radiotherapy had a median survival of 18 months compared to 14 months in those who did not receive radiotherapy ( P=0.073). In limited disease patients there was a trend to prolonged survival in patients randomized to receive radiotherapy.