Twenty-six women with metastatic breast cancer were treated with intensive Adriamycin (Adria Laboratories, Columbus, OH) as a single agent administered for three successive days once a month. Dosing started at 25 or 30 mg/m2/d three times, and was escalated by 5 mg/m2/d monthly to maximal tolerance based on hematologic, mucosal, or cardiac toxicities. Four patients (15%) had complete remissions (CRs) pathologically proven, and six others (23%) sustained complete CRs, but were found to have microscopic residual tumor (three) or refused biopsy (three). Twelve patients (46%) attained partial remission (PR). The overall response (85%) and CR rates (38%) were approximately double those reported with conventional Adriamycin doses. Median unmaintained remission duration for the ten patients in CR was 11 months. Cardiotoxicity, determined by radionuclide physiologic studies, occurred in 16 patients at a mean dose of 459 mg/m2; three patients developed reversible congestive failure. There were no toxic deaths. The median overall survival was 18 months. These data suggest that there is steep dose responsiveness to Adriamycin in metastatic breast cancer, and that more effective techniques for using Adriamycin may exist than those conventionally used.