Objectives : To study the effects of Kumsooyukkun-jeon on asthma. Methods : Asthma was induced to Balb/c mice with ovalbumin using the method of Hatfield et al. We measured the 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 mucous-secretory cells in the bronchus, morphology of the bronchus, ultramicroscopical appearance of surface of trachea and number of cilia and mucous-secretory cells by scanning electron microscope. Results : 1. Hypertrophy of mucous membrane of trachea and bronchus and bronchioles in the lung, peritracheal, peribronchus and peribronchiolar inflammatory cell infiltration, and mucoid exudate deposition the lumen were observed in control groups but these phenomena were recovered in the Kumsooyukkun-jeon groups. 2. Cellular compartments including neutrophil and eosinophil were increased in the BALF of control groups but these phenomena were recovered in the Kumsooyukkun-jeon groups. 3. Degranulation and decrease of the numbers of mast cells were detected in the trachea of control groups. However, these phenomena were recovered in the Kumsooyukkun-jeon groups. 4. Shedding, decrease of cilia cell and increase of mucous-secretory cells in the surface of the trachea were measured in control groups but these phenomena were recovered in the Kumsooyukkun-jeon groups. Conclusions : It is considered that Kumsooyukkun-jeon has somewhat favorable effects on asthma.