A phase II study of vindesine in 41 evaluable patients demonstrated the drug to be active in heavily pretreated patients with breast cancer, non-Hodgkin's lymphoma, and other tumors. There were two partial responses in 11 patients with breast cancer (18%) and five partial responses and one complete response in 11 patients with non-Hodgkin's lymphoma (40%). Other responses were seen in small cell carcinoma of the lung, ovarian carcinoma, and Hodgkin's disease. Prior vinca exposure did not adversely affect the response rate. Neutropenia was dose-limiting. Neurotoxic effects occurred in 10% of the patients. A high incidence of local tissue reactions at the injection site (27%) could be reduced by a careful administration technique. Vindesine should be studied further in combination with other agents.