Evaluation of any therapeutic modality for carcinoma of the breast requires prolonged follow-up. Between 1965 and 1968, 870 women with primary unilateral breast cancer were treated surgically at our institution. To achieve a study group that could be meaningfully analyzed, the authors identified and excluded all patients with pre-existing life-threatening disease, incomplete (palliative) operation, multiple lesions, or fixed lesions. There remained 530 patients (322 treated with radical and 208 treated with modified radical mastectomy). No overall statistical difference in 5-year survival to death from breast cancer was noted between the radical (82.1%) and the modified radical (87.0%) mastectomy group. Recently, the authors updated that series, now with 10 to 16 years of follow-up (minimum, 10 years). Two hundred eighty-one patients were alive at 10 years. The 10-year survival from breast cancer after radical (74.5%) and modified radical (74.2%) mastectomy was almost identical. The 10-year node-negative survival was 86.0% and the node-positive survival was 56.3% (P = 0.0001). Results were compared according to age, tumor site, absolute number of involved nodes, histologic features, grade, size, and adjuvant treatment. A numeric combination of these variables was constructed and used as a prognostic score. These results suggest that, with equal long-term efficacy in the treatment of breast cancer, the cosmetically and functionally superior modified radical mastectomy should remain the procedure of choice in the surgical treatment of carcinoma of the breast.