Therapy with tamoxifen has been used in 109 woman with advanced breast carcinoma; 75 of them had been previously submitted to ovariectomy, hormonal treatment and or polychemotherapy. Tumors were localized in the breast in 21 cases, in the lymph nodes in 34 cases, in the dermis in 32 cases; there were 26 cases with lung metastases and 62 cases with bone metastases. Fifty-one patients showed multiple tumor involvement, but only 57 patients referred to have pain. Objective responses were obtained in 36 percent of the cases (15 patients with complete remission and 25 responses over 50 percent). An additional 30 percent of minor responses was also obtained. Pain disappeared in 68 percent of the cases. According to the tumor localization, objective responses were obtained in 26 out of 62 osseous metastases, in 16 out of 34 lymph node involvement, 12 out of 26 lung metastases, 12 out of 32 dermic localizations, and 6 out of 21 breast tumors. Drug tolerance was excellent, and maximum therapeutic response occurred between 3 and 15 months after beginning of treatment with tamoxifen. These results encourage the usefulness of tamoxifen in the treatment of patients with advanced breast carcinoma.