Introduction: Although sinusitis is a clinical diagnosis, imaging studies are used to assess the extent of the disease and demonstrate sinonasal anatomy. Concha bullosa is the pneumatization of the middle turbinate and one of the most common variations of sinonasal anatomy. Concha bullosa may lead to narrowing or even complete blockage of the entrance to the middle meatus. Objectives: This work aimed to detect the relationship between concha bullosa and incidence of sinusitis. Subjective and methods: 100 subjects with age ranged from 20 to 50 years were included in this study. They were divided into study and control groups. All subjects were examined and C.T for all were performed. Results: Significant difference was found between study and control groups as concha bullosa was found in 80%of patients with chronic rhinosinusitis in contrary to 10% of subjects not suffered from chronic rhinosinusitis. Conclusion: concha bullosa may be one of the predisposing factors of chronic rhinosinusitis and so surgical manipulation during FESS is important to avoid recurrence of the disease.