Between 1955 and 1984, 376 patients with locoregionally advanced breast carcinoma were treated at The University of Texas M. D. Anderson Cancer Center with mastectomy and irradiation and without adjuvant chemotherapy. Patients with inflammatory carcinoma or synchronous bilateral primary tumors were excluded. There were 202 patients with Stage IIIA disease and 174 patients with Stage IIIB disease (AJC Staging--1983). In 124 patients the surgical management was confined to the breast only--total mastectomy (BR) and in 252 dissection of the axilla was performed--extended total, modified radical, or classic radical mastectomy (BR + AX). All patients had postoperative irradiation. The follow-up period ranged between 8 and 34 years. At 10 years, the actuarial disease-specific, relapse-free survival (DSRFS) rate for the entire group was 40%, and the actuarial locoregional control rate was 82%. For patients with Stage IIIA disease the DSRFS was 48% and locoregional control rate was 88%. For those with Stage IIIB disease, the figures were 30% and 74%, respectively. Most of the failures occurred within 5 years of the mastectomy and essentially all occurred within 10 years. When analyzed by type of surgery, both the locoregional control and DSRFS rates were improved by the axillary dissection, the difference being largely caused by fewer axillary node recurrences after dissection of both the breast and axilla than after removal of the breast alone. In the 252 patients in whom the axilla was assessed, the number of positive nodes was a powerful predictor of both locoregional control and survival. The DSRFS rates at 10 years for patients with 0, 1-3, and greater than or equal to 4 positive nodes were 63%, 48%, and 30%, respectively. The actuarial locoregional control rates at 10 years exceeded 95% for patients with 0-3 positive nodes and 75% for those with greater than or equal to 4 nodes. These results show that locoregionally advanced breast cancer is not a uniformly fatal disease when treated without chemotherapy and provide a baseline upon which to assess the value of adjuvant systemic therapy for this stage of disease.