Thirty-five patients with a mean age of 60.6 years (44-78 years, 22 male, 13 female) with advanced low-grade non-Hodgkin's lymphoma (NHL), chronic lymphocytic leukemia (CLL), or prolymphocytic leukemia (PLL) were treated every 4 weeks with prednimustine 100 mg/m2 p.o. d 1-d 5 and mitoxantrone 8 mg/m2 i.v. d 1 and d 2. Seven patients had CLL, one lymphocytic NHL, two PLL, 13 immunocytoma, nine centroblastic/centrocytic NHL, and three centrocytic NHL. Twenty-five patients were pretreated. The subjective toxicity of the treatment was mild, with no WHO grade-3 alopecia, polyneuropathy, cardiotoxicity, mucositis, nausea, or vomiting. Hematologic side effects with WHO grade-4 granulopenia and thrombopenia were experienced by 26% and 23% of the patients, respectively. The overall response rate (CR+PR) was 72% for lymphoma patients and 37% for CLL patients, with a median remission duration of 14.6 months. The maximum response was achieved after a median of two treatment courses. Prednimustine with mitoxantrone is a subjectively well tolerated treatment for low-grade malignant NHL, to be further evaluated in phase-III studies. The regimen may shorten the duration of treatment, saving time-consuming out-patient visits and costs.