To detect the expression and correlation of cyclooxygenase-2 (COX-2) and nuclear factor-kappa B (NF-kappaB) in nasal polyps co-cultured with clarithromycin, and to investigate their roles in CRS pathogenesis. Nasal polyps from 11 patients with chronic rhinosinusitis (CRS) were cultured for 24 hours with different doses of clarithromycin (0, 10(-6), 10(-5), 10(-4) mol/L). Western blot and real time fluorescence quantitative PCR were performed to detect the expressions of COX-2 and NF-kappaB subunits. The expression levels of COX-2, NF-kappaBp50 and NF-kappaBp65 were most high in control groups (0 mol/L clarithromycin). The expressions of COX-2, NF-kappaBp50 and NF-kappaBp65 were dose-dependently attenuated as the concentrations of clarithromycin increased. Significantly positive correlation between RNA expressions of COX-2 and NF-kappaB subunits in each CRS group was confirmed by Pearson correlation treatment (P<0.05). The increased expression of COX-2 is involved in the inflammation in CRS. It indicate that clarithromycin may play an anti-inflammatory effect on CRS by decreasing the synthesis of COX-2 through blocking NF-kappaB pathway.