Data on 162 women (90 premenopausal and 72 postmenopausal) with metastatic breast cancer randomized to receive cyclophosphamide, Adriamycin (doxorubicin) and 5-fluorouracil (CAF) on two Eastern Cooperative Oncology Group (ECOG) protocols were analyzed. Twenty-three percent had complete remission; 39% had partial remission; 28% had no change; and 3% had disease progression. Of those patients in whom receptors were known, response rates were 65% for estrogen (ER)-receptor positive and 70% for ER-negative patients. The median duration of response was 11.4 months. The median survival time from the start of CAF was 20.2 months. The response rate, time to treatment failure (TTF), and median survival time were superior in the premenopausal women. These differences ceased, however, to be statistically significant in logistic models. Factors significantly associated with longer TTF and longer survival were as follows: one or two organs with metastases (TTF, P less than 0.0001; survival, P less than 0.0001); dominant site other than soft tissue (TTF, P less than 0.0001; survival, P = 0.05); and an initial good performance status (TTF, P = 0.007; survival, P = 0.02). Patients with ER-positive disease had a significantly longer median survival time (P = 0.003).