A phase II clinical trial of VP-16-213 was carried out in 71 patients with small cell and non-small cell carcinoma of the lung. Forty-eight evaluable cases consisted of 36 small cell carcinomas, 7 epidermoid carcinomas, 4 adenocarcinomas and one unclassified carcinoma. VP-16-213 was administered by drip infusion at dosages of 60-100mg/m2/day for 5-consecutive days at 3-4 week intervals. Twelve of 36 (33.3%) small cell carcinomas had partial responses, while no responses were obtained in non-small cell carcinomas. Median duration of responses was 46 days (range 31-133 days). The dose limiting toxicity was leukopenia. Median number of days to nadir was 14 days and median numbers of days for recovery was 11 days. Nausea (38%), vomiting (12%), anorexia (45%) and alopecia (74%) were major clinical toxicities although these were mild or reversible. We concluded that VP-16-213 was useful in the treatment of small cell lung cancer and the dose schedule used in this study was recommendable with small dose reduction for further trial of combination chemotherapy.