Thirty children with malignant solid tumors receiving adriamycin had serial evaluation of left ventricular (LV) function by echocardiography. The echocardiographic studies showed a progressive decrease in myocardial contractility as evidenced by changes in several parameters of LV function with increasing cumulative doses of the drug. Using the patients as their own controls, serial echocardiography appears to be a reliable method for detecting early alteration of cardiac function in the asymptomatic patient. This technique may prove useful to prevent cardiomyopathy secondary to adriamycin and to prolong therapy beyond the currently established limits.