Thirty-two patients with advanced breast cancer were treated with a combination of vincristine (1 mg/m2, not exceeding 2 mg, administered intravenously on day 1), adriamycin (40 mg/m2 administered intravenously on day 1), and cyclophosphamide (200 mg/m2 administered orally for 4 days on days 3-6). Courses were repeated at 21-28-day intervals. The mean age of the patients was 57 years (range, 30-79 years) and 18 patients were postmenopausal. None of the patients had received prior chemotherapy although 15 had prior endocrine treatment. Objective response was observed in 23 (72%) of the 32 patients and 9 responses (28%) were complete. The median remission duration was estimated to be 22 months. Median survival has not been reached but exceeds 24 months with a median time of follow-up of 17 months. Toxicity was acceptable and included mild nausea, vomiting, alopecia, and paresthesias. Only one instance of serious infection and no instances of bleeding were observed. The addition of vincristine to combination chemotherapy with adriamycin and cyclophosphamide appears to prolong the remission duration and survival in patients with advanced breast cancer to a greater extent than is achieved with adriamycin and cyclophosphamide alone.