Primary radiation therapy for early breast cancer is a combination of limited breast surgery for the removal of gross disease, and moderate doses of radiation for the control of residual subclinical disease. The results from retrospective studies using primary radiation therapy indicate that high levels of local tumor control with good cosmetic results can be achieved. Preliminary results from a prospective randomized clinical trial indicate that radical mastectomy and primary radiation therapy result in equivalent survival rates. Primary radiation therapy is a reasonable alternative to mastectomy when adequate surgical and radiotherapeutic expertise is available to deliver this treatment.