Early experience with extracranial CT has shown this diagnostic method to be highly accurate in evaluating the liver, pancreas, kidneys, retroperitoneum, and pelvis. The diagnosis of neoplasm, inflammatory changes, and normal moophologic variants is possible. Initial data indicat that this modality may assume a primary role in the evaluation of the liver, pancreas, and retroperitoneum (e.g., the differentiation of medical from surgical jaundice and the distinction of solid from cystic lesions). In the thorax, the results appear far less dramatic. CT scans rarely surpass the diagnostic accuracy of conventional radiologic studies. Initial results indicate a need for studies comparing CT with radionuclide examinations, ultrasonography, and other conventional radiographic procedures as well as for evaluating its use in radiation therapy planning and follow-up.