One hundred and six patients with advanced breast cancer were treated with chemoendocrine therapy consisting of adriamycin (40 mg/m2) i.v. on day 1 and cyclophosphamide (130 mg/m2) i.v. daily for 5 days every 3 weeks, ftorafur (500 mg/m2) and tamoxifen (40 mg) orally daily. Of 82 evaluable patients, 16 showed complete response (20%), 32 partial response (39%), 32 no change (39%), and two progressive disease (2%). The overall response rate was 59%, and the median duration of response was 16.3 (3.5-67+) months with a median survival time from the start of chemoendocrine therapy of 25.5 (3.5-67+) months. The median survival time of responders (32.5 months) was significantly longer than that of non-responders (15.3 months). The major toxicities were hair loss, G1 symptoms, and hematological toxicity, but these were clinically well tolerated. No serious cardiac, renal or liver damage was seen. These results indicated that the addition of tamoxifen to the ACF regimen increased the number of complete responses and prolonged the survival time of responders.