One hundred and thirteen patients (62 males and 51 females, aged 5-70 years) with chronic sinusitis seen between January 1995 and December 1998 in the Ear, Nose and Throat (ENT) Diseases Clinic of University of Ilorin Teaching Hospital, Ilorin, Nigeria are presented. A provisional diagnosis of chronic sinusitis was made if there were at least two of the following signs and symptoms: nasal blockage, nasal discharge, post nasal drip, excessive sneezing or halitosis. The radiographic abnormalities observed include gross mucosal thickening; haziness; complete opacity and air-fluid level. Seventy-eight (69.0%) showed abnormality in one or both maxillary antra; 39 (34.5%) in the ethmoid; 13 (11.5%) in the frontal; and 1(0.9%) in the sphenoidal sinuses. Thus the maxillary sinus was observed to be the most commonly involved in the disease process, while the sphenoidal sinus is the least commonly involved. This is consistent with findings in most similar studies.