The general aspects and newer applications of two-dimensional, contrast, and doppler echocardiography in the assessment of congenital heart diseases are reviewed. The M-mode techniques are presently of limited value as diagnostic tool and are confined to few detailed findings which are often missed at standard examination: particularly the M-mode is useful in the visualization of pulmonic valve which shows characteristic abnormalities in pulmonary hypertension. Two-dimensional echocardiography has opened a new era of investigation in the evaluation of congenital heart diseases. It has enhanced the ultrasonic resolution in the delineation and connection of intracardiac structures, providing a systematic approach to the diagnosis of complex cardiac abnormalities. The left and right ventricular chambers can be identified through the position and morphology of their atrioventricular valves and papillary muscles, and by evaluation of the mitral-semilunar valve continuity. The newest utilization of standard echocardiography involves the prenatal diagnosis of congenital heart diseases by way of intrauterine echocardiography: the fetal heart can be visualized in several planes by transabdominal approach in the mother. With careful attention, a complete examination including four and five chambers view of the ventricle and short axis view of the great arteries, can be accomplished in almost all cases, allowing an accurate determination of many congenital defects. The contrast technique was originally used for identifying right cardiac chambers on M-mode echocardiograms: it provides excellent times resolutions and an accurate analysis of flow related events across the cardiac structures.(ABSTRACT TRUNCATED AT 250 WORDS)