Background and Objective: Sinonasal polyposis is a chronic disease in the nose and paranasal sinuses caused by chronic inflammation. Nasal septum deviation (NSD) is a common anatomical abnormality which can cause chronic sinonasal polyposis. The aim of the present study was to investigate the correlation of this abnormality with pathologic, clinical findings and primary diseases in sinonasal polyposis patients. Materials and Methods: This case series study was undertaken based on the available data. The clinical history of 122 patients with sinonasal polyposis was studied. The patients were divided into two different groups, namely, with and without NSD and their clinical data were carefully reviewed. The patients’ tissue samples were also reviewed pathologically. Results: 60.6% of the patients were without NSD while 39.3% were with NSD. Inflammatory cell infiltrations, severity of edema, fibrosis and epithelium structure were the same in both groups. There was a significant correlation between the snoring and NSD (p=0.03), but no further significant correlations were found in other clinical symptoms. The radiological findings revealed no significant correlation with NSD. Patients with aspirin intolerance were relatively more in the group without NSD (p=0.02), but no other significant correlation was found between presence or absence of nasal septal deviation and allergy or bronchial asthma. Conclusion: Based on this study, NSD has no effect on the pathologic findings of sinonasal polyposis. There is also no correlation between polyp type and affected sinuses though, it has been proved that it can cause nighttime snoring. It seems that this anatomical abnormality can increase the occurrence of sinonasal polyposis, but has no determinative role in the occurrence of inflammatory processes and clinical symptoms.