A total of 25 patients with advanced breast cancer were treated weekly with i.v. 5-fluorouracil at 350 mg/m2, folinic acid at 500 mg/m2, and epidoxorubicin at 35 mg/m2 as first-line chemotherapy for a maximum of 18 cycles. In all, 24 patients were evaluable for response. Overall, 1 patient achieved a complete response and 11 patients showed a partial response, for an objective response rate of 50%; the median duration of response was 18.3+ months and median survival amounted to 18.8+ months. Side effects were generally mild, with grade II leukopenia occurring in 10 patients and grade III leukopenia, in 1 patient. Other toxicity included nausea and vomiting (82%), diarrhea (48%), stomatitis (48%), and alopecia (92%), all of which were mainly restricted to WHO grades I and II. Our results suggest that leucovorin modulation of 5-fluorouracil can safely be incorporated into combination chemotherapy with epidoxorubicin on the investigated schedule. The observed response rate appears comparable with that obtained with other first-line regimens.