Infusional 5-fluorouracil (F) with cisplatin (C) and epirubicin (E), so-called infusional ECF, is a highly active new schedule against locally advanced or metastatic breast cancer. Cisplatin, however, is a major contributor to toxicity and usually requires inpatient treatment. In an attempt to overcome this, we have investigated the effect of substituting carboplatin for cisplatin in our original infusional ECF regimen. Fifty-two patients with metastatic (n = 36) or locally advanced/inflammatory (n = 16) breast cancer were treated with 5-fluorouracil 200 mg m-2 day-1 via a Hickman line using an ambulatory pump for for 6 months, with epirubicin 50 mg m-2 intravenously (i.v.) and carboplatin AUC5 i.v. every 4 weeks, for six courses (infusional ECarboF). The overall response rate (complete plus partial) was 81% (95% CI 67%-90%), with a complete response rate of 17% (95% CI 6-33%) in patients with metastatic disease and 56% (95% CI 30-80%) in patients with locally advanced disease. Median response duration and survival for metastatic disease was 8 and 14 months respectively, and two patients with locally advanced disease have relapsed. These results are very similar to those previously achieved with infusional ECF. Severe grade 3/4 toxicity was low. Infusional ECarboF is a highly active, well-tolerated, outpatient regimen effective against advanced/metastatic breast cancer and now warrants evaluation against conventional chemotherapy in high-risk early breast cancer.