To study the accuracy of 2-dimensional echocardiography (2-D echo) in estimating mitral and tricuspid anular diameter, 2-D echo estimates were compared with autopsy measurements of anular diameter in 21 children studied by echo within 30 days of death. The mitral anulus was measured from the left parasternal long axis view and the apical or subcostal 4-chamber image and the tricuspid anulus from the 4-chamber view. Comparable measurements were made from the autopsy specimen with calipers. The correlation coefficient for echocardiographic vs autopsy measurements was 0.79 (standard error of the estimate 2.8 mm) (mitral long axis r = 0.76, mitral 4-chamber r = 0.85, tricuspid 4-chamber r = 0.76). Echo measurements exceeded the corresponding autopsy measurements by an average of 17%; this was at least partially attributed to shrinkage of the specimen during fixation. Thus, 2-D echo may be used to provide a reasonable estimate of mitral and tricuspid anular diameter.