Objectives : In this study, the author tried to examine whether Cheogjogupye-tang (淸燥救肺湯, CGPT) and Yieum-jeon (理陰煎, YEJ) significantly affect in vitro and in vivo mucin secretion, MUC5AC gene expression in airway epithelial cells and contractility of isolated tracheal smooth muscle of rabbit. Materials and Methods : For in vitro experiment, confluent hamster tracheal surface epithelial (HTSE) cells were chased for 30 minutes in the presence of CGPT and YEJ to assess the effects of the agents on mucin secretion by enzyme-linked immunosorbent assay (ELISA), with removal of oriental herbal medicine extract from each agent-treated sample by centrifuge microfilter. Also, the effects of the agents on TNF-alpha or EGF-induced MUC5AC gene expression in human airway epithelial cells (NCI-H292) were investigated. Possible cytotoxicities of the agent were assessed by examining both LDH release from HTSE cells and the rate of survival and proliferation of NCI-H292 cells. For in vivo experiment, hypersecretion of airway mucin and goblet cell hyperplasia was induced by exposure of rats to $SO_2$ over 3 weeks. Effects of CGPT and YEJ orally administered for 1 week on in vivo mucin secretion from tracheal goblet cells of rats and hyperplasia of goblet cells were assessed using ELISA and histological analysis after staining the epithelial tissue with alcian blue, respectively. Also, the effects of CGPT and YEJ on contractility of isolated tracheal smooth muscle were investigated. Results : (1) CGPT significantly inhibited in vitro mucin secretion from cultured HTSE cells. However, YEJ did not affect in vitro mucin secretion; (2) CGPT and YEJ did not affect hypersecretion of in vivo mucin and hyperplasia of tracheal goblet cells; (3) CGPT and YEJ slightly increased the expression levels of TNF-alpha or EGF-induced MUC5AC gene in NCI-H292 cells; (4) CGPT and YEJ inhibited acetylcholine-induced contraction of isolated tracheal smooth muscle of rabbit; (5) CGPT and YEJ did not affect LDH release from HTSE cells and the survival and proliferation of NCI-H292 cells. Conclusion : The results from the present study suggest that CGPT and YEJ mainly affect the expression of mucin gene rather than secretion of mucin and do not show remarkable cytotoxicity to respiratory epithelial cells.