In order to study the effect of oral administration of Mawhangyounpye-tang against to asthma, astham was induced to allergy-sensitive Balb/c mouse with ovalbumin using method of Hatfield et al (1997). The changes of diameter lumen of upper portion of the trachea, lung weight, gross appearance of lung, histological profiles of lung and trachea, numbers of cellular compartments in the bronchoalveolar lavage fluid (BALF), numbers and morphology of the mast cells in the trachea, numbers of mucus-secretory cell in the broncus, morphology of the bronchus, ultramicroscopical appearance of surface of trachea and number of cilia and mucous-secretory cells by scanning electron microscope. Obtained results were as follows. 1. The diameters of trachea lumen were significantly decreased in asthma induced control groups and these decreasing were result from hypertrophy of mucous membrane. However, these phenomena were dramatically recovered in the Mawhangyounpye-tang dosing groups. 2. Lung weights and black spots, which were result from infiltration of inflammatory cells, were significantly increased in asthma induced control groups but these phenomena were dramatically recovered in the Mawhangyounpye-tang dosing groups. 3. Hypertrophy of mucous membrane of trachea and bronchus and !bronchioles in the lung, peritracheal, peribronchus and peribronchiolar inflammatory cell infiltration, and mucoid exudate deposit in the lumen were observed in asthma induced control groups but these phenomena were dramatically recovered in the Mawhangyounpye-tang dosing groups. 4. Cellular compartments including neutrophil and eosinophil were dramatically increased in the BALF of asthma induced control groups but these phenomena were dramatically recovered in the Mawhangyounpye-tang dosing groups. 5. Mast cell degranulation and decreasing of the numbers of mast cells were detected in the trachea of asthma induced control groups. However, these phenomena were dramatically recovered in the Mawhangyounpye-tang dosing groups. 6. Shed, decreasing of cilia cell and increasing of mucous-secretory cells in the surface of the trachea of asthma induced control groups but these phenomena were dramatically recovered in the Mawhangyounpye-tang dosing groups. In conclusion, it Is considered that Mawhangyounpye-tang has somewhat favorable effect on the asthma because the asthma specific series of abnormalities in respiratory system were decreased after oral administratin of Mawhangyounpye-tang in this study. In future, it is needed that the toxicological and dosagespecific study of Mawhangyounpye-tang to use against asthma with safe.