Lack of spatial registration of imaging transducers is a major technical limitation of two-dimensional (2-D) echocardiography. Volume scanning of the heart, or three-dimensional (3-D) echocardiography, is achieved by using a 3-D spatial registration device with a conventional 2-D scanner, or by using a high speed, phased-array real-time scanner. Three-dimensional spatial coordinate systems may be external or internal systems with respect to the scanning transducer. With external systems data acquired from several cardiac windows may be integrated and reconstructed. An external coordinate system allows creation of a "line of intersection" display to guide image positioning in the nonvisualized dimension orthogonal to the real-time image. Use of this display has shown a significant, threefold improvement in the accuracy of image positioning and the reproducibility of chamber measurements. Three-dimensional echocardiography using polyhedral surface reconstruction also yields more accurate measurement of ventricular volume and new measurements of total endocardial surface area and infarct surface area. Computer modeling and 3-D computergraphic displays hold promise of valuable new methods of communication, data analysis, and surgical planning.