Cordyceps sinensis has been clinically used for the treatment of recovering fatigue, promoting the production of body fluid and qi, resolving sputum and arresting cough. Recent studies showed that Cordyceps sinensis produced immune-modulatory, anticarcinogenic and antioxidative effects. But, there are lack of studies regarding the effects of Cordyceps sinensis on the asthma. So, this study was performed to investigate the oral administrated effects of this herb against the disease. Asthma was induced to Balb/c mouse by i.p. injection and aerosol immunization with ovalbumin, and the change of the eosinophil number in the bronchoalveolar avage fluid(BALF) was observed. Concentrations of Interleukine-4(IL-4), Interleukine-5(IL-5) in BALF and splenocyte were assessed by ELISA, ImmunoglobinG(IgG) and ImmunoglobinE(IgE) from serum were calculated by same method. We found that the effects of Cordyceps sinensis in asthma mouse was implicated in reductions of IL-4, IL-S released from type2 T helper (Th2) cell, and decreases of IgE from plasma cell. These findings suggest that Cordyceps sinensis can produce anti-asthmatic effect, which may play a role in allergen-induced asthma therapy.