Thirty-six patients with stage III and IV Hodgkin's disease and non-Hodgkin's lymphoma, who had become refractory to conventional chemotherapy, were treated with VM-26. Complete remissions were documented in two patients with diffuse histiocytic lymphoma. Six patients (four with non-Hodgkin's lymphomas and two with Hodgkin's disease) had partial remissions. The overall response rate was 22% (eight of 36 patients). Hematologic toxicity was the most frequent dose-limiting toxicity. Nonhematologic toxic effects were mild and acceptable. This study demonstrates that VM-26 can produce tumor responses in refractory lymphomas. The Eastern Cooperative Oncology Group is currently planning two new phase II studies to incorporate VM-26 with other active new agents, one involving hexamethylmelamine and the other involving cis-dichlorodiammineplatinum(II).