The authors undertook a study to test the feasibility and efficacy of doxorubicin (Dox) administered as continuous infusion (c.i.) in the treatment of advanced breast cancer patients. All patients were previously treated as first line chemiotherapy with bolus-administered Dox; then they received a second line treatment without Dox. Patients were eligible if they had advanced measurable breast cancer, resistant to first and second line chemotherapy regimens, and if previous Dox treatment had been performed more than one year before, and after ECG and cardiac echographic controls were performed. A dose of 4.5 mg/m2/day of Dox was planned for 10 consecutive days in c.i. through a central venous catheter, repeated at 28 day intervals, for a maximum of 10 cycles. Among the 71 patients, 56 received 3 or more treatment courses; 10 patients refused further therapy after the first cycle. Objective responses were achieved in 25 patients (35%), 3 complete and 22 partial remissions. Stabilization was obtained in 11 patients (16%). The median time to progression was 9.3 months. Obviously, haematological toxicity was the major problem; in the 71 patients, 376 courses were administered (mean number of courses per patient: 5.3): grade 4 neutropenia (WHO system) occurred in 2 patients, and grade 3 in 9 patients; while one patient died of gastric haemorrhage. Severe cardiac toxicity occurred in only one patient who died 24 hours after the beginning of therapy, with ECG lateral ischemia. Grade 4 stomatitis was observed in only one patient.(ABSTRACT TRUNCATED AT 250 WORDS)