Identifying the predisposing factors is therefore important in understanding the pathophysiology of chronic rhino sinusitis. Main etiology of respiratory CRS includes structural anatomical obstruction, recurrent upper airway infections,common allergies, biofilm formation and less commonly mucosal ciliary dyskinesia, MPS (mucopolysaccharidosis) and cystic fibrosis. These etiological factors which impairs the mucociliary clearance and causes stasis of secretions which constitutes the primary pathophysiology for the chronic rhino sinusitis. CT scan was done for these 100 cases with THOSHIBA Multi detector 16 slice CT machine. 0.5mmhigh resolution with 1mm reconstruction, coronal,sagittal and axial sections were reviewed. The presence of anatomical variations and sites of involved sinuses based on CT findings were investigated. Maxillary sinusitis was seen in 63 cases out of which, 34 cases of maxillary sinusitis were associated with anatomical variations.Ethmoid bulla in 2 cases.Uncinate process pathologies noted in2 cases.