To study the natural history of the alterations in cardiac function produced by Adriamycin therapy, serial M-mode echocardiograms, electrocardiograms, and systolic time intervals were obtained in 15 patients prior to Adriamycin therapy and at 3-month intervals during and 1 year after cessation of therapy. The echocardiographic E-point septal separation increased from a median 0 dose value of 0.40 cm to 0.70 cm (P less than 0.003) at the time of the maximum dose of Adriamycin. The electrocardiographic frontal plane voltage decreased 13% (P less than 0.008) and the pre-ejection period/left ventricular ejection time ratio increased from a median value of 0.37 to 0.40 (P less than 0.01) during this same period. During the first year after Adriamycin was discontinued, no significant change was noted in any of these values. Thus, as a group, the slight deterioration of ventricular function that occurred during Adriamycin therapy remained unimproved during the 1-year followup period.