A clinical evaluation of peptichemio (40-45 mg/m2/day for 3 days every 3-4 weeks) was conducted in 32 patients with advanced breast cancer, 28 of whom were evaluable for both toxicity and response. The overall response rate was 18% (one complete remission and four partial remissions), with a median duration of 4 months (range, 2-6). The major side effects were cumulative myelotoxicity, phlebitis, mild nausea, and vomiting. A posttreatment heparin infusion was used to prevent phlebitis.