Thirty-one elderly patients with measurable advanced breast cancer entered this phase II study. A dose of 15 mg/m2/day of Idarubicin (IDA) for 3 consecutive days every 3 weeks was given orally. Mean total cumulative dose of IDA received was 175 mg/m2 (range: 45-475 mg/m2). Mean number of cycles given was four (range: 1-15). Out of 27 evaluable patients, three achieved a complete response (CR), four had a partial response (PR) (CR + PR = 26 +/- 17%), nine showed no change, and 11 had a progressive disease. Median time to progression was 83 days (range: 19-728 days). Out of 26 patients evaluable for toxicity, hematologic toxicity at day 21 was moderate: neutropenia grades 3 and 4 = 16% of cycles: two patients had grade 1 thrombopenia; and three patients, grade 3. No cumulative hematologic toxicity was detected. Nonhematologic toxicities consisted of nausea and vomiting in 72% of patients [World Health Organization (WHO) grades 3 and 4 = 8%)] and alopecia in 76% (WHO grades 2-3 = 38%). Grade 1 stomatitis occurred in 4% of cycles. Chemotherapy was discontinued in one patient because of drop of left ventricular ejection fraction (LVEF) from 0.62 to 0.44 at a cumulative IDA dosage of 322 mg/m2. The results of this study show that IDA is an active drug in elderly patients with advanced breast cancer. Due to its simplicity of administration IDA deserves further investigations in combination with other drugs.