To evaluate the cosmetic outcome of conservative surgery (CS) and radiation therapy (RT) for early-stage breast cancer and its stability over time, we reviewed the records of 593 patients treated from 1968 to 1981. The breast appearance was scored as "excellent," "good," "fair," or "poor". Median follow-up was 76 months (range, 37 to 186 months). Cosmetic results were generally excellent or good. The percents of excellent, good, fair, and poor results at three years were 65%, 25%, 7%, and 3%, respectively. Patients not receiving adjuvant chemotherapy were more likely than those receiving chemotherapy to have excellent scores at five years (71% vs 40%). Tumor size also influenced cosmetic outcome: 73% of patients with T1 tumors vs 55% with T2 tumors had excellent scores at five years. Our results were stable over time: of 36 patients assessable at seven years whose cosmetic scores were good or excellent at three years, 34 (94%) continued to have good or excellent scores, and only two (5%) deteriorated to fair. We conclude that the cosmetic results achieved with CS and RT are good to excellent in approximately 90% of patients and that these results remain stable for at least seven years.