A total of 120 infants, children, and teenagers, who were admitted to the Department of Pediatrics, Severance Hospital from April 1989 to August 1989, were examined by cross-sectional echocardiography. Right and left atrial and ventricular dimensions and areas were measured in the parasternal, apical, and subcostal views. Dimensions of the inferior caval vein, the pulmonary and the aorta were obtained in the parasternal, suprasternal, and subcostal views. The results were as follows : 1) Statistical analysis showed no difference between boys and girls. 2) For all parameters, a positive linear correlation was found with age, height, weight, and body surface area. The best correlation was with body surface area. 3) The correlation was further improved if the logarithmic values of the measurements and body surface area were considered. 4) Measurements by cross-sectional echocardiography are clinically useful, especially in the study of the right-sided cardiac structures that are difficult to evaluate with M-mode echocardiography, but the problems of reproducibility have to be taken into account.