A phase II study of epirubicin (EPI) was performed on 65 eligible lung cancer patients. EPI was administered intravenously at the dosage of 60 mg/m2 for non-small cell lung cancer (NSCLC) and 75 mg/m2 for small cell lung cancer (SCLC) at the interval of three to four weeks. The response rate of 57 measurable patients was 7.0% (predicted true response rate was 1.9-17.0%). In SCLC, the overall response rate was as low as 8.3% (2/24), but a better response rate, 20% (2/10), was observed in patients given no prior therapy. In NSCLC, the response rate was 6.1% (2/33) as a whole and 12.5% (2/16) in patients given no prior therapy. We were able to conclude that EPI was a moderately active agent in SCLC and marginally effective in NSCLC. Although the dose limiting factor was leukopenia, its incidence and degree seemed low as compared with adriamycin (ADM). As for alopecia or GI tract side effects, those associated with EPI appeared less acute than those produced by ADM. No cardiac toxicities were observed, partly because of the low cumulative maximum dose of 311 mg/m2 used in our study.