The authors treated 83 patients with carcinoma of the breast using a combination of external and interstitial irradiation at Los Angeles County--University of Southern California Medical Center and Southern California Cancer Center between February 1, 1974, and May 31, 1977. All 30 patients who had T1 and T2 lesions, and who were followed for a minimum period of 24 months (24-50 months) are clinically still free of disease. Thirty-nine of 53 patients with T3 and T4 lesions, who were followed for a minimum of 30 months (30-56 months) are still alive with local control. Details of treatment techniques, dosimetry, results and complications are presented.