Rejection surveillance is critical to successful heart transplantation, and infant recipients have necessitated the use of noninvasive measures. The survival, incidence of rejection, and accuracy of echocardiography in predicting treatable rejection, as detected on right ventricular endomyocardial biopsy, were prospectively studied in infants. The survival rate (82%) and rejection rate (1.4 rejection episodes per 100 patient days) of infants who underwent transplantation during the study were comparable to other studies that used heart biopsy only. Echocardiography was 98% accurate at predicting biopsy results. The sensitivity of echocardiography was 92%, and the specificity was 98%. We conclude that echocardiography can be used successfully for primary rejection surveillance in infants and that right ventricular biopsy is infrequently required.