We evaluated left and right ventricular diastolic functions by pulsed Doppler echocardiography in 16 children with dilated cardiomyopathy and in 20 healthy age-matched control subjects. The cardiomyopathy group demonstrated an abnormal relaxation pattern of the left ventricle. In the cardiomyopathy group compared to normal subjects, peak early filling velocities (43.3 +/- 11 cm/s versus 60.4 +/- 11 cms/s, p < 0.01), the corresponding velocity-time integrals (3.3 +/- 1.4 cm versus 4.6 +/- 1.2 cm, p < 0.01) and the ratio of peak early filling velocity to late filling velocity (1.22 +/- 0.47 versus 1.49 +/- 0.23, p < 0.05) were significantly lower whereas isovolumic relaxation time was significantly longer (58.9 +/- 19.8 ms versus 49.7 +/- 8.9 ms, p < 0.05). In addition, right ventricular diastolic filling was also impaired in children with dilated cardiomyopathy. Peak early filling velocities (41 +/- 7.9 cm/s versus 47.5 +/- 8.8 cm/s, p < 0.05) and the corresponding velocity time integrals (3.0 +/- 1.0 cm versus 3.87 +/- 1.1 cm, p < 0.05) were significantly decreased, while isovolumic relaxation time was significantly increased (60.6 +/- 16.3 ms versus 52.2 +/- 12.8 ms, p < 0.05) in the cardiomyopathy group. The study suggests that abnormalities of both right and left ventricular diastolic function may occur, and should be searched for, in pediatric patients with dilated cardiomyopathy.