Imbalance between oxidant formation and antioxidant defense is associated with the pathogenesis of several chronic inflammatory disorders of the respiratory tract. Therefore, a role of oxidative stress in chronic upper respiratory tract can be anticipated. The objective of the present study was to investigate the antioxidant defense systems; namely, glutathione and uric acid in chronically inflamed mucosa of patients with chronic sinusitis as a trial to determine the role imposed by oxidative stress in the pathogenesis of chronic sinusitis. This study included 11 patients (8 men & 3 woman) assigned to undergo surgical procedure for complaints of nasal obstruction caused by deviated nasal septum as control group, in addition to another 10 patients with sinusitis (8 men & 2 women) and assigned to undergo functional endoscopic sinus surgery. Mucosal sinus specimens from osteomeatal area, i.e., the uncinate process, were obtained during surgery, homogenized in 10 mg/mL ice-cold phosphate-buffered saline, centrifuged, and the supernatant was separated and stored at -80°C until for use. All samples were examined for estimation of sample concentration, per gram-wet weight, of lipid peroxides (LP), reduced glutathione (GSH), oxidized glutathione (GSSH), and uric acid. The obtained data showed significantly (P< 0.001) increased sample levels of LP and decreased GSH and uric acid in patient group compared to the control group. Whereas, there was a non¬significant (P>0.05) difference in GSSH levels between both groups. Moreover, there was a negative significant correlation between sample levels of LP and GSH (r=-0.635, P<0.05) and uric acid(r=-0.733, P<0.05) in patient group. We could conclude that increased levels ofLP and decreased levels of both GSH and uricacid in patients with chronic sinusitis illustrated a diminished antioxidant defense, which may be associated with the pathogenesis of upper respiratory tract disorders. These findings may offer perspectives for pharmacotherapeutic intervention with antioxidants. Tanta Medical Journal 2000