The objective of this paper is to study the correlation between sinonasal involvement and type of cystic fibrosis (CF) in Israeli's CF patients. The comparative study includes 70 CF patients: 40 typical and 30 atypical CF patients. History and physical examination data were recorded, including endoscopic nasal examination as well as sinus computer tomography scan. The data collected from the two groups were statistically analyzed. Twenty-seven percent of atypical CF patients compared with 2.5% of typical CF patients had CF presenting symptoms of chronic rhinosinusitis (CRS) or obstructive nasal polyps (p < 0.001). Although severe CRS was found slightly more often in patient with atypical CF (43 vs. 32.5%), this difference did not reach statistical significance. Nine patients with severe CRS underwent endoscopic sinus surgery. Among these patients, six (66.6%) had atypical CF and only three (33.3%) had typical CF (p = 0.09). In conclusion, severe CRS is a common diagnosis among patients with typical and atypical CF disease. In the current study, no significant difference in the frequency of CRS was found between the two groups. High awareness toward the diagnosis of atypical CF, careful medical history focusing on sinonasal involvement and physical examination, including nasal endoscopy, for all CF patients (typical and atypical CF) may contribute to an early detection and treatment of significant sinonasal involvement, and may improve the quality of life of the patients.