The stabilities of doxorubicin hydrochloride, daunorubicin hydrochloride, zorubicin, and aclacinomycin A hydrochloride were studied in various infusion fluids at ambient temperature. Reversed-phase high-pressure liquid chromatographic procedures developed and used in these studies employed internal standards and readily separated each drug from its degradation products. Dilute solutions of the anthracyclines were prepared by appropriate dilutions of the reconstituted solutions of the formulated products with 5% Dextrose Injection, USP (D5W); 0.9% Sodium Chloride Injection, USP (NS); Lactated Ringer's Injection, USP (LR); and Normosol-R pH 7.4. The stability of the anthracyclines was dependent on the pH of the admixture solution which, in turn, was dependent on infusion fluid composition. Daunorubicin and aclacinomycin A exhibited acceptable stability (equal to 90% of the original concentration) in D5W, NS, and LR for more than 48 hours. Doxorubicin manifested similar stability in the first two fluids. Zorubicin showed similar stability only in Normosol-R pH 7.4 fluid for 22 hours.