Thirty-eight females with advanced breast cancer who had failed prior chemotherapy were entered in a randomized study of rubidazone (150 mg/m2 iv over 1 hour) versus Adriamycin (60 mg/m2 iv over 5 minutes), both given every 4 weeks. The two treatment groups each contained 19 patients and were similar with respect to age, menopausal status, dominant disease status, Eastern Cooperative Oncology Group performance score, and prior hormonal therapy and chemotherapy exposure. No regressions (complete or partial) were observed with rubidazone, but four (21%) patients achieved regressions (one complete and three partial) with Adriamycin. Considering all cycles, hematologic toxicity included leukopenia (wbc count nadir of less than 4000/mm3) in 88% of patients receiving rubidazone and in 89% of those receiving Adriamycin. Three of eight patients treated with Adriamycin after rubidazone failure achieved a regression. Rubidazone appears to be of little value in the treatment of patients with advanced breast cancer who have failed prior chemotherapy.