An automatic computer technique was designed to produce three-dimensional (3D) images of bony anatomy on a cathode ray tube (CRT) from computerized tomography (CT) data. The authors transferred CT scan data of a cadaver and 11 patients to a computer system via magnetic tape. An automatic edge extraction algorithm generated an outline of bone specified by a range of CT numbers for each scan slice. These outlines were stacked in the computer and various graphics options used to represent the 3D anatomy of bone on a high-resolution CRT screen. The 3D image data were interfaced with a three-axis computer numerically controlled milling device to produce solid models of these bone images. Comparison of the dimensions of the solid models of the femur, hemipelvis, and femoral medullary canal to the actual cadaver specimen demonstrated that the models were accurate in size to within 1-3 mm. These 3D images and solid models will be helpful for preoperative diagnosis, surgical planning, and customized prosthesis manufacture in complex orthopaedic cases.