The usefulness of computerized tomography for the diagnosis of various disease in the head & neck and maxilloficial areas has already been recognized. The recent developments made in the computer technology have yielded a 3-dimensional image(3D-CT), which has proven to be helpful in the diagnosis as well as the treatment planning of the disease in head & neck and maxillofacial areas. We performed 3D-CT in various fields of head & neck and maxillofacial, areas and obtained the following results. 1) Excellent images were obtained from cases of maxillofacial fractures, congenital facial deformities, bone destruction due to tumors and tumor with calcification. 2) In the diagnosis of laryngeal and tracheal stenosis, 3D-CT proved to be more useful than 2-dimensional image(2D-CT) or the tomogram. 3) The images were of little helpful in soft tissue diseases because the differentiation from the surrounding tissues proved to be difficult. 4) Vascular disorders, when enhanced, will probably be clinically useful.