Right ventricular endomyocardial biopsy has been the traditional gold standard for determining cardiac transplant rejection. Although endomyocardial biopsy has proved useful in guiding rejection therapy, this procedure is not without risk. The objective of the present study was to determine whether a noninvasive method for assessing cardiac diastolic function would be of value in predicting biopsy scores. Doppler echocardiographic indices of left ventricular function were compared with biopsy scores in 43 studies from 23 patients (age 50 +/- 8 years). The average time from transplant to echocardiographic study was 1.5 years. Standard clinical indices of diastolic function failed to predict biopsy results. The A-Ar interval, evaluated in 36 studies, was found to significantly decrease (p < 0.003) with increasing biopsy scores. Preliminary results suggest that this echocardiographic parameter may prove useful in predicting biopsy results.