To detect the effect of p38 mitogen activated protein kinase (p38MAPK) and cyclooxygenase-2 (COX-2) on the expression of mucin5AC (MUC5AC) in human nasal mucosa induced by histamine in vitro, and to investigate the pathogenesis of mucus hypersecretion in allergic rhinitis (AR).Western blot was performed to detect the protein expressions of p38MAPK, COX-2 and MUC5AC in nasal mucosa induced by histamine or blocked by selective inhibitors of p38MAPK and COX-2 of different concentration gradient.Weak expressions of p38MAPK. COX-2 and MUC5AC were detected in normal nasal mucosa in vitro. The protein expressions of p38MAPK. COX-2 and MUC5AC increased in nasal mucosa induced by histamine in a dose-dependent manner. The histamine induced protein expressions of COX-2 and MUC5AC were dose-dependently attenuated by selective inhibitor of COX-2, namely NS-398. No apparent influence of NS-398 on the expression of p38MAPK was observed. The histamine induced protein expressions of p38MAPK, C()X-2 and MUCbAC dose-dependently decreased after nasal mucosa was treated by selective inhibitor of p38MAPK, namely SB203580. And no significant change of MUC5AC protein expression induced by NS-398 or SB203580 was observed.Our findings indicated that the histamine-induced increased expression of MUC5AC by activated p38MAPK/COX-2 may be a possible pathogenesis of mucus hypersecretion in AR.