The results of treatment with 5-fluorouracil, imidazole carboxamide, BCNU and prednisolone (FIB-P) salvage chemotherapy in 60 patients with heavily pretreated advanced breast cancer are presented. For most of the patients (82%) this was the third line of chemotherapy. Performance status (ECOG) was 1, 2 and 3 in respectively 13, 27, and 20 patients. Predominant metastatic sites were: soft tissue (3/60, 5%), bone (22/60, 37%), and viscera (35/60, 58%). Tumor burden (number of affected organic systems) was 1, 2 and 3 or more in respectively 18, 24 and 16 patients. Average dose intensity received was 0.74 (range, 0.47-0.98); the average number of cycles was 3.8 (range, 2-8). Objective response (CR + PR) was observed in 22 patients (1 CR, 21 PR), with a response rate of 37% (22/60). Median duration of remission was 7 months (range, 3-15). Tumor burden was the only pretreatment patient characteristic that significantly influenced the remission rate (p less than 0.10). Dose intensity significantly affected tumor response (p less than 0.05). Toxic side effects (gastrointestinal disorders, alopecia and myelotoxicity) were generally moderate and tolerable. No treatment-related death occurred. FIB-P proved to be an active salvage chemotherapy in heavily pretreated patients with advanced breast cancer.