Effective palliation of metastatic breast carcinoma (MBC) after the failure of front-line chemotherapy for advanced disease, often based on the use of anthracyclines and taxanes, is quite difficult to achieve due to the development of dominant neoplastic cellular clones highly resistant to further therapy. Therefore the therapeutic index of second and third line chemotherapeutic treatments is usually quite low. Thirty patients with MBC with progressive disease after anthracycline-based chemotherapy as first line therapy were treated with l-FA 100 mg/m2/day and 5FU 1000 mg/m2/day ad continuous venous infusion for 96 hours every 4 weeks. Most patients (60%) had multiple sites of disease at entry and had visceral lesions as the dominant site of disease. Twenty-eight patients were evaluated for objective response: two patients had clinically progressive disease before restaging after the third cycle of chemotherapy. These patients were considered progressive disease since all patients were included in an intent-to-treat analysis. Nine patients achieved partial response for an overall response rate of 30% (intent-to-treat analysis) with a median duration of 9.5+ months (range 4.0/14.0 months), and disease stability was obtained in 10 cases (33%) with a median duration of 5.5 months (5-11). Progressive disease was recorded in 9 patients. After a median follow-up of 11 months, the overall median survival time of the whole series of patients was 14.0+ months. Objective responses were recorded both at visceral and bone sites. Chemotherapeutic treatment was generally quite well tolerated. No toxic deaths were recorded. Among gastrointestinal side-effects grade 3 stomatitis was noted in 30% of patients, and grade 3 diarrhea in 10% of cases. Grade 3-4 leukopenia was observed in 23% of patients, but significant episodes of febrile neutropenia were limited (2 patients). Grade 3 thrombocytopenia was seen only occasionally in 1 patient. Grade 1 anemia was recorded in 10% of patients. Hand-foot syndrome was noted in 2 patients (7%). Cardiotoxicity was minimal. The combination of 5FU and high-dose I-FA given as 96 hour continuous venous infusion was active, at least in terms of the overall response rate, against anthracycline refractory metastatic breast carcinoma. These results compare favourably with bolus 5FU/FA or other salvage regimens in terms of antineoplastic activity, and is well tolerated both subjectively and objectively by most patients.