A total of 70 patients with malignant lymphomas refractory to one or more chemotherapeutic regimens were treated with iv amsacrines (m-AMSA and m-AMSA lactate). Of 58 evaluable patients, 12 had Hodgkin's disease and 46 had non-Hodgkin's lymphoma. Twenty-nine of the evaluable patients received m-AMSA and 29 received m-AMSA lactate. The amsacrines were recycled every 3 weeks. The doses of m-AMSA were 90-120, 70, and 25-30 mg/m2/day for 3 days, respectively. All patients treated with m-AMSA lactate received a single dose of 225 mg/m2. In Hodgkin's disease, the response rate was 58.3% (one complete response among 12 patients), and in non-Hodgkin's lymphoma, the response rate was 30.4% (six complete responses among 46 patients). The median duration of response was 3 and 5 months, respectively. The response rate was unfavorably affected by the presence of extra-nodal disease and a Karnofsky performance status less than 80. There was no important difference in the incidence and duration of response between m-AMSA and m-AMSA lactate. After vomiting, myelosuppression was the most frequent observed toxic effect. One patient showed an unexpected fatal bone marrow aplasia following the first course of 90 mg/m2. This study indicates that m-AMSA and m-AMSA lactate are active and moderately toxic in previously treated malignant lymphomas. Thus, amsacrines could be effectively incorporated into salvage polydrug regimens.