A randomized comparative study of anticancer chemotherapy CE (CDDP plus etoposide) and CE-AVN (ACNU, VCR plus procarbazine) was carried out on 27 patients with small cell lung cancer (SCLC) without previous chemotherapy. In CE therapy, 12 patients received injection of CDDP (80 mg/m2 on day 1) and etoposide (75 mg/m2 on day 1-5) every 4 weeks (Protocol 1). Fifteen patients received 2 courses of CE and 1 course of AVN therapy (ACNU 100 mg/m2 on day 1, vincristine 0.7 mg/m2 once a week and procarbazine 50 mg/day, daily) for 6 to 8 weeks (Protocol 2). One patient (8%) and 2 patients (20%) achieved complete response with Protocol 1 and 2, respectively. Seven patients (58%) and 9 patients (60%) achieved partial response with Protocol 1 and 2, respectively. The median survival time (MST) was 12 and 14 months, and duration of remission was 4.5 and 7 months in patients treated with Protocol 1 and 2, respectively. No significant difference in MST and duration of remission in each group was observed. However, 2 patients (13%) treated with Protocol 2 survived more than 3 years. Both protocols were well tolerated with only moderate gastrointestinal symptoms, mild bone marrow toxicity and alopecia.