Conservative treatment of breast cancers confined to the lower quadrants often leaves a residual deformity. In order to prevent these poor cosmetic results, 20 patients with lower quadrant cancers have been treated since 1986 at the Institut Curie by wide lumpectomy combined with immediate remodeling of the gland by nipple-bearing superior pedicle mammaplasty and preoperative (9 cases) or postoperative (11 cases) irradiation. The contralateral breast was always rendered symmetrical at the same time. The mean weight of resection was 248 gm, and the resection margins were always free of tumor. The treatment protocols were not modified by the addition of mammaplasty to lumpectomy, and this combination did not induce any significant complications. The mean follow-up was 4.5 years (range 1 to 7.5 years). There was one case of local recurrence; there were four cases of metastases. In this series, the oncologic results were identical to those of conventional treatment by lumpectomy and irradiation. The cosmetic result was good or very good in 75 percent of patients and 91 percent of patients in the group in which mammaplasty was performed prior to irradiation. Treatment of breast cancers by superior pedicle reduction mammaplasty and irradiation is indicated in tumors located in the lower quadrants, whose size in relation to the breast volume is such that conventional conservative treatment by lumpectomy and irradiation would achieve a poor cosmetic result.