The toxicity and efficacy of the combination of pirarubicin (THP), etoposide, and vincristine were investigated in a phase I trial. The dose of THP was modified in steps of 10 mg/m2 or 5 mg/m2 differences, starting with 40 mg/m2 i.v. on day 1. Doses of etoposide (100 mg/m2 i.v. days 1-3) and vincristin 2 mg i.v. day 1) remained constant. The schedule was repeated every 3 weeks. A minimum of four patients were recruited at each dose level. The maximum tolerated dose (MTD) was defined as follows: toxicity WHO grade 3 and 4 in five of eight patients of one dose step (exception: leukocytopenia at the time of nadir WHO grade 4 is relevant for the MTD). Currently, 20 patients have been treated. The administered dose levels of THP were (mg/m2); 40 (5 patients), 50 (4 patients), 55 (6 patients), and 60 (5 patients). Screening of cardiac function (ECG, ultrasound cardiography) was performed at the start of the treatment and before each course. There were no signs of cardiotoxicity up to a cumulative dose of 360 mg/m2. Leukocytopenia WHO grade 3 was observed in seven courses (12%), and grade 4 was observed in two courses (3%) as main side effects. The subjective tolerability (nausea, vomiting, and alopecia) was mild to moderate. We decided upon 55 mg/m2 MTD because WHO grade 4 leukocytopenia developed in one patient after the first course and two not conclusively clarified early deaths occurred at the 60 mg/m2 pirarubicin dose level. Eighteen patients were evaluable for response: one CR (6%), eight PR (44%), four NC (22%), one EP (6%), and four ED (22%). This means a response rate of 50% and a median survival time of 10 months. We have initiated a phase II study with the elaborated schedule.