OBJECTIVE OF STUDYTo determine the clinical, radiological and histopathological changes in maxillary antrum compared to ethmoid sinuses in patients with chronic sinusitis with nasal polyposis.STUDY DESIGNThis is a prospective observational study conducted in a tertiary care hospital.MATERIALS AND METHODSA total number of 30 primary cases of inflammatory nasal polypi, not responding to conservative measures, were evaluated clinically and radiologically. They underwent endoscopic sinus surgery, and all sinuses were cleared of diseases. Histopathological evaluation of both maxillary sinus and ethmoid sinuses was done and compared.RESULTSAmong 30 patients with 60 nasal cavities studied, nearly all showed partial or complete opacity of their maxillary antrum and blocked osteomeatal complexes on radiology. But, only a few patients (16.67%) showed frank polypi in their antrum intra-operatively. On histopathology, antral mucosa showed rare involvement, and the submucosa showed variable grades of inflammation, but it was significantly less compared to ethmoids.CONCLUSIONAlthough maxillary antrum gets involved clinically in nearly all polyposis cases, pathological involvement is unlikely compared to ethmoid sinuses. Thus, it indicates a secondary inflammatory change in maxillary sinuses rather than primary involvement.