Quelamycin (triferric doxorubicin) is a derivative of Adriamycin with different pharmacologic properties. Our phase I clinical study of quelamycin includes 37 patients with a wide spectrum of solid tumors. The recommended dose in good-risk patients is 150 mg/m2, given as a 1-hour infusion every 3 weeks. The dose-limiting factor appears to be myelosuppression, especially leukopenia. Other toxic effects include gastrointestinal intolerance and alopecia. Chills and fever are commonly encountered and might be due to an excess of free iron in currently available preparations. Cardiotoxicity could not be properly assessed. An objective antitumor effect was seen in patients with lung, gastric, colon, and ovarian carcinomas as well as osteogenic sarcoma. Further preclinical and clinical studies with an improved pharmaceutic formulation of the drug are highly desirable.