We retrospectively investigated amrubicin hydrochloride(AMR)monotherapy as second or thirdline chemotherapy for small-cell lung cancer(SCLC)and assessed its efficacy and safety. AMR was intravenously administered at 25-45mg/m2 for 3 consecutive days every 3-4 weeks. Fifty-three patients were enrolled. Response rates and median survival times were as follows: total cases, 32% and 7. 4 months; sensitive relapse cases, 64% and 16. 4 months; refractory relapse cases, 27% and 5. 9 months. Neutropenia was major toxicity(Grade 3 or 4 was observed in 72% of the subjects), whereas nonhematologic toxicities were mild. Treatment with AMR appeared effective in SCLC patients previously treated with chemotherapy. On the other hand, it must be used carefully because of its relatively severe hematologic toxicities.