Chronic asthma is considered as an incurable disease in modern society. This study focused on development of an animal model for the chronic asthma to investigate new drugs from traditional herbal medicine. And we tested the animal model with a typical prescription, Chungsangboha-tang and tried to find biochemical markers such as catecholamines and cAMP in serum, and as densities of beta-receptor in lung tissues. SD rats were actively sensitized by exposure to ovalbumine (OA). Ten days after sensitization, rats were challenged with OA aerosol by nebulizer six times every three days. Mucin was increased in bronchoalveolar lavages (BALs) after antigen (OA) challenge. Serum concentration of epinephrine was decreased significantly although there were not changed much in serum concentration of cAMP and the densities of beta-receptor in lung tissues. Chungsangboha-tang (5 g/kg/day) was given orally to ovalbumin-sensitized rats (n=8) for 15 days. Mucin in bronchoalveolar lavages (BALs) was increased significantly after treatment of Chungsangboha-tang although concentrations of epinephrine and cAMP were not changed significantly. The densities of beta-receptor in lung tissues were not different from those of controls. These results suggest that the ovalbumin-sensitized rats can be a good animal model of chronic asthma and Chungsangboha-tang is a possible drug in the treatment of chronic asthma.