Allergic contact dermatitis (ACD) is a type IV delayed hypersensitivity reaction that results from exposures andsubsequent sensitization to an environmental chemical. Crataegus Pinnatifida (CP) is commonly used to improvespleen function, remove retention of food, and promote blood circulation. This study is designed to investigate theeffects of CP on ACD induced by 2,4-dinitrochlorobenzene (DNCB) in mice. In this experiment, the effects of CPon changes in body weights, ear and dorsum skin thicknesses, ear weights, clinical aspects on the dorsum skin,histopathological changes, spleen weights, cytokines were investigated. In addition, the effects on the proliferationrates of splenocytes were also investigated in vivo and vitro study. In results, CP spread (CPS) group and CP spread and administered (CPS+Adm) group showed decrease in spleenweights. In CPS+Adm group, dorsum skin thicknesses were decreased significantly compared to control group. CPtreatment diminished erythema, desquamation and keratosis which were induced by repeated painting of DNCB. In histopathological observation, spongiosis and edema were diminished in CPS and CPS+Adm group. CP led todecrease in the proliferation rates of splenocytes in vivo and vitro. In conclusion, these data suggest that CP can decrease symptoms of ACD, so CP is useful to treat patient withACD.