From 1978 through 1984, 103 postmenopausal patients with locally advanced breast cancer (T4 N1-2-3 MO) were treated by definitive radiotherapy (XRT, 35 patients) or mastectomy and postoperative radiotherapy (RM + XRT, 68 patients). A control group of 35 of the 68 RM + XRT patients was selected by matching several prognostic variables with the XRT group. Patients were followed for 4 to 10 years. At 5 years the probabilities of overall survival and relapse-free survival were 49.9% and 33.2% for XRT patients and 49.2% and 42.8% for RM + XRT patients, respectively (with no significant difference). The probability to remain free of local-regional progression at 5 years, with censoring of deaths, was 71.9% in the XRT group and 79.8% in the RM + XRT group. Of the patients treated with definitive radiotherapy, those who received 60 Gy or more to the primary tumor had a significantly better 5-year rate of local control: 88.0% vs. 68.0%, p less than 0.05. Our results suggest that adequate doses of radiotherapy can provide long-term local-regional control in a large proportion of survivors and can spare mastectomy in most patients, without however achieving substantial improvements in the poor survival results.