Three-dimensional ultrasound is a new modality finding its way into clinical practice. Most of the major ultrasound vendors are now developing three-dimensional ultrasound capabilities. We expect that although three-dimensional ultrasound will not replace two-dimensional ultrasound, many additional benefits will be identified and its use will continue to grow. The ability to evaluate anatomy and pathology with multiplanar and surface-rendered images provides physicians additional valuable clinical information. Volume data allows for a specific point in space to be evaluated from many different orienta tions by rotating, slicing, and referencing the slice to other orthogonal slices. It also allows for new volume-rendering displays that show depth, curvature, and surface images not available with conventional methods. The current limitations of image resolution, intuitive interfaces for obtaining and displaying optimal images, and technologic limitations for data storage and manipulation (including real-time three-dimensional ultrasound) will surely be overcome in the near future.