From January 1980 to August 1982 the Cancer and Leukemia Group B conducted a prospective randomized trial comparing chemoendocrine therapy with T-CAF (cyclophosphamide, adriamycin, and 5-fluorouracil plus tamoxifen) to CAF alone in postmenopausal women with advanced breast cancer. The patients were stratified by estrogen receptor (ER) status into three groups: ER-negative, ER-positive, ER-unknown. They were also stratified by dominant site of metastatic disease: visceral and other (osseous and/or soft tissue). A total of 246 eligible patients were enrolled in the study; 232 were evaluable and constitute the basis for this report. The study revealed that there was no difference in overall response frequency or response duration between T-CAF and CAF; there was no difference in response between T-CAF and CAF in ER-positive or in ER-negative patients; and there was no difference in response between T-CAF and CAF by dominant site of metastatic disease. The expected advantage of T-CAF over CAF, especially for ER-positive patients, was not observed.