The anti-tumor efficacy and safety of idarubicin (IDR) were investigated among patients in whom the standard therapy for malignant lymphoma had failed or who had suffered a recurrence. IDR was administered at a dose of 12 mg/m2 or 15 mg/m2 by a single i.v. bolus, and this dosage regimen was repeated every 3 weeks. Among total of 21 evaluable patients, there were 3 CRs and 1 PR, for an overall response rate of 19.0% (4/21). All patients who attained CR were cases which had recurred after receiving combination chemotherapy including doxorubicin. Adverse reactions were bone marrow suppression, including leucopenia (90.5%), neutropenia (95.2%), and thrombocytopenia (47.6%); gastrointestinal symptoms such as nausea/vomiting (42.9%) and stomatitis (9.5%); alopecia (23.8%) and fever (19.0%). These results indicate that IDR is effective against refractory malignant lymphoma.