In order to obtain an accurate evaluation of nasal and paranasal sinus disease in cystic fibrosis patients, 75 patients with a proven cystic fibrosis diagnosis have been investigated using the following standard techniques: questionnaire, ENT examination, endoscopical examination, sinus X-rays, and in 31% of the cases a CT scan. The analysis of results shows that nasal obstruction is the most frequent symptom (32%) and that nasal polyps are present in 43% of the cases. Endoscopic examination seems to be of great interest in giving a more accurate picture of nasal and paranasal sinus disease. Analysis of CT scan images leads the authors to describe a new and specific entity in nasal and paranasal sinus disease in cystic fibrosis patients: the pseudomucocele. In this report, the authors discuss the various aspects of pseudomucocele, attaching particular importance to the CT scan results.