Sixty-two patients, presenting to the Nasal Dysfunction Clinic at the University of California, San Diego, were radiographically examined with plain sinus x-rays and computed tomographic (CT) scans. The x-rays were evaluated independently, and the reported findings were compared. In maxillary sinuses the CT and plain film observations corresponded poorly with a concordance of 77%. There was a tendency to overread the plain films. In the ethmoid sinuses the lack of concordance between CT scans and plain films was 76%, and a tendency to underread the plain films was noted. In the lower nasal compartment the correspondence between CT and plain film readings was 57%, with a notable tendency to overread the plain films. In the olfactory recess, the CT/plain film concordance was 66%. At our institution, a sinus CT series costs $400; a conventional sinus series costs $102. The CT radiation dose is 5.2 to 6.5 cGY compared with 1.4 cGY for plain films. We conclude that plain films are unreliable and no longer routinely indicated for the evaluation of nasal and paranasal sinus disease. When radiographic evaluation is indicated a limited CT series provides superior information. Exceptions may include children and some cases of sinus disease isolated to a single sinus.