Pyunkang-hwan (Pyunkang-tang) extract (PGT) is a traditional folk medicine for controlling diverse pulmonary diseases including bronchitis, tonsiltis and pneumonitis. We investigated whether PGT significantly affects secretion, production and gene expression of airway mucin using in vivo and in vitro experimental models reflecting the hypersecretion and/or hyperproduction of mucus observed in inflammatory pulmonary diseases. For in vivo experiment, effect of PGT was checked on hypersecretion of pulmonary mucin in sulfur dioxide-induced bronchitis in rats. For in vitro experiment, confluent NCI-H292 cells were pretreated with PGT for 30 min and then stimulated with EGF (epidermal growth factor), PMA (phorbol 12-myristate 13-acetate) or TNF-${alpha}$ (tumor necrosis factor-${alpha}$) for 24 h. The MUC5AC mucin gene expression and mucin protein production were measured by RT-PCR and ELISA. The results were as follows: (1) PGT inhibited the expression of MUC5AC mucin gene induced by EGF, PMA or TNF-${alpha}$ from NCI-H292 cells, respectively; (2) PGT also inhibited the production of MUC5AC mucin protein induced by the same inducers from NCI-H292 cells, respectively; (3) PGT inhibited secretion of mucin in sulfur dioxide-induced bronchitis rat model. This result suggests that PGT can regulate secretion, production and gene expression of airway mucin.