This paper describes the results of a randomized trial comparing alternating chemotherapy with standard chemotherapy and of a trial of dose intensive chemotherapy with or without recombinant human granulocyte-colony stimulating factor (G-CSF) in small cell lung cancer (SCLC). 1) Between April 1985 and May 1988, the Japan Clinical Oncology Group conducted a randomized phase III trial of cyclophosphamide, doxorubicin and vincristine (CAV) versus cisplatin and etoposide (PE) versus CAV alternating with PE (CAV/PE). Three hundred patients were entered in the study, and 288 of them were eligible for analysis. The response rates for PE (78%) and CAV/PE (76%) were significantly higher than the rate for CAV (55%) (p < 0.01). The median survival time (MST) with CAV/PE (11.8 months) was superior to that with CAV (9.9 months) (p = 0.027) or that with PE (9.9 months) (p = 0.056); however, the survival advantage of CAV/PE disappeared when the data were adjusted for prognostic factors. These results have shown that CAB/PE is a reasonable approach for the management of SCLC. 2) Between May 1989 and September 1991, we carried out a randomized study to determine whether the dose intensity of the weekly CODE (cyclophosphamide, Oncovin, doxorubicin and etoposide) chemotherapy could be increased by the addition of G-CSF support. Sixty-three patients were entered in this study. The use of G-CSF was associated with a reduced incidence of neutropenic fever and an increase in the dose intensity. The MST for the patients treated with CODE plus G-CSF (58 weeks) was significantly longer than that for the patients treated with CODE alone (36 weeks). The results of this study showed that dose intensive weekly chemotherapy may improve the outcome of patients with ED-SCLC.