Women's appraisal of the cosmetic result and their psychosocial adjustment after a standardized segmental mastectomy for benign or malignant breast disease was analyzed on the basis of a mailed questionnaire, which was satisfactorily answered by 263 (92%) of 285 women operated on consecutively. The overall result was favorable: 96.5% of the patients found the new appearance of their breast very good (30.7%), good (44.0%), or acceptable (21.8%). Women with a benign diagnosis ran a two-fold higher risk of being discontented with the new appearance of the breast than those with breast cancer. Complications of radiation therapy, preoperative concern that the breasts are important for the appearance, and anxiousness about the cosmetic result were associated with a significantly elevated risk of being less satisfied with the outcome. The main finding that it is possible to perform a locally radical operation that is highly acceptable to the woman is relevant to the surgical management of potentially malignant mammographic lesions and also to the scientific strategies for future evaluation of breast-conserving treatment modes in malignant disease.