A total of 40 patients with metastatic breast cancer were treated with 120 mg/m2 i.v. epirubicin every 3 weeks for a maximum of 10 cycles. Nine achieved a complete response and 17 showed a partial response, for an objective response rate of 65% (95% confidence interval, 47%-83%); the median duration of response was 7 months (range, 1-15 months) and median survival amounted to 13 months (range, 2-20 months). Leucopenia (grade 2 or 3) was seen in 14 patients on day 21 of the cycle. A subset of nine patients underwent blood counts on day 10, when all had marked neutropenia (< 1 x 10(9)/1). Other toxicity was frequent and included nausea/vomiting (80%), alopecia (95%) and stomatitis (35%). Five patients showed a significant fall in cardiac output, but this reverted to normal after treatment. Epirubicin should have a role in the development of high-dose regimens for the treatment of advanced breast cancer.