Computed tomography (CT) has added an important new dimension to the radiological evaluation of diseases of the paranasal sinuses and face. Using transverse and coronal scans, accurate assessment of the character and extent of mass lesions in this region can be achieved. Erosion of thin bony laminae and involvement of soft tissue structures of the face can be seen. Most important. CT is capable of precisely defining the extension of lesions into the pterygopalatine fossa, orbit, and cranial cavity, information that is essential for therapeutic planning. © Raven Press. New York.