The records of 53 patients treated with Adriamycin, 17 of whom developed congestive heart failure and 36 of whom received a similar total dose of Adriamycin without developing congestive heart failure, were analyzed for factors associated with Adriamycin cardiomyopathy. The risk of cardiomyopathy was significantly greater in patients who developed a larger than or equal to 30% decrease in limb-lead QRS voltage. Concurrent cyclophosphamide and mediastinal radiotherapy lowered the cumulative Adriamycin dose necessary for the development of cardiac toxicity. Uncontrolled hypertension also appears to be a risk factor in potentiating the development of Adriamycin cardiomyopathy at lower doses. Congestive heart failure was more likely to be fatal if it developed shortly after the last dose of Adriamycin. These findings can be utilized to increase the safety of Adriamycin therapy in the future.