In a phase II study we evaluated the effect and toxicity of a new alkylating agent, PTT-119, in 26 patients with non-Hodgkin's lymphomas (NHL) resistant to or relapsed after other chemotherapy. PTT was scheduled by escalating the dose from 2.0 to 3.3 mg/kg every 3 weeks. Among 21 evaluable patients with NHL, 12 (57%) showed a good response (CR + PR) to PTT-119. Tolerance was acceptably good; no major side effects related to liver, cardiac, or renal toxicity were recorded. The most commonly recorded side effects were nausea and vomiting, alopecia, and phlebitis; diarrhea and drug-related fever were rarely seen. This report indicates a potential usefulness for PTT-119, a non-cross-resistant alkylating agent, in the treatment of NHL.