A phase II trial of esorubicin (4' deoxydoxorubicin) was conducted by the Southwest Oncology Group in 88 assessable patients with non-Hodgkin's lymphoma (NHL) and Hodgkin's disease (HD) at the time of first relapse. Esorubicin was administered at two dose levels: 25 mg/m2 for patients at risk for excessive myelosuppression, and at 30 mg/m2 for all others at 21-day intervals. Overall, 33 of 88 patients (38%) responded to treatment including three complete remissions (CRs; 3%) and 30 partial remissions (PRs; 34%), with the median duration of response lasting 6.2 months. Response rates did not differ significantly by histologic subtype: 31% of 26 patients with favorable NHL, 33% of 43 patients with unfavorable NHL, and 58% of 19 patients with HD. Twelve of 33 responding patients (36%) had relatively durable remissions lasting from 1 to more than 4 years. Leukopenia (less than 3,000 cells per microliter) was seen in 65 of 88 patients (74%) and was severe (less than 1,000 cells per microliter) in 20 of 88 patients (23%). Clinical signs or symptoms of congestive heart failure were not seen and the ejection fraction (EF) fell 10% to 20% in three patients. Esorubicin is an active agent in patients with NHL or HD at the time of first relapse.