Effective microorganism (EM) fermentation extract has been widely used for agricultural and environmental application. It has been recently revealed that EM cocktail treatment may be effective for treatment of diseases including cancer. In the present study, effectiveness of EM cocktail to control asthma was investigated using a mouse model of allergic asthma. Asthmatic mice sensitized and intranasally challenged with OVA were orally given EM fermentate ($EM-1^{(R)}$) during antigen challenge. Administration of $EM-1^{(R)}$ resulted in a significant reduction in airway hyper-reactivity (AHR) and airway recruitment of total leukocytes and eosinophils. Cytokine (IL-4, IL-5 and $IFN{gamma}$) levels in bronchoalveolar lavage fluid (BALF) and lung tissues were not altered by $EM-1^{(R)}$ treatment. However, IL-13 level in BALF was considerably lower in $EM-1^{(R)}$ treated mice than in controls. Moreover, Ag-specific IL-4, IL-5 and IL-13 production of draining lymph node cells were markedly downregulated by $EM-1^{(R)}$ treatment when compared to controls, whereas their $IFN{gamma}$ production was not significantly different. Those data show that $EM-1^{(R)}$ treatment suppresses type 2 helper T (Th2), but not type 1 helper T (Th1), cell response. This finding was also supported by serum antibody data showing that IgE and IgG 1 levels in $EM-1^{(R)}$ treated mice were significantly lower than in controls, while IgG2a level was not significantly different between two groups. In conclusion, oral administration of $EM-1^{(R)}$ attenuates asthmatic manifestations including AHR and airway recruitment of eosinophils in a mouse model and which possibly results from selective inhibition of Th2 cell response to allergen. Our data also suggest that $EM-1^{(R)}$ may be effectively applied for control of allergic asthma.