Carminomycin, an anthracycline antibiotic discovered in the Soviet Union, possesses antitumor activity and is chemically related to adriamycin and daunorubicin. The toxic effects of carminomycin observed in single-dose toxicologic studies in mice iv (4.5-13.5 mg2) and po (18.9-52.2 mg/m2), rats iv (6.0-21.0 mg/m2), dogs iv (1.0-16.0 mg/m2) and po (16.0-80.0 mg/m2), Rhesus monkeys po (24.0-144.0 mg/m2); and in multiple-dose studies in dogs iv (18 doses 0..6-5.0 mg/m2, 2X/week) and rats sc (9 doses 3.0-12.0 mg/m2, 3X/week), were dose-related and primarily manifested as suppression of hematopoiesis. Other toxicities observed included nephrotoxicity, gastrointestinal toxicity, decreased spermatogenesis, decrease in size and activity of the prostate and seminal vesicles, and ovarian alterations. In general, these toxicities were reversible in surviving animals during recovery periods. Cardiotoxicity, similar to that seen with adriamycin sc (13 doses 12.0 mg/m2, 1X/week) was not observed with carminomycin sc (13 doses 6.0 mg/m2, 1X/week).