A study was carried out to examine the effects of 23 kinds of crude drugs and 3 kinds of blended Chinese traditional medicines on Type I and Type IV allergic reactions. Forty eight-hr homologous PCA in rats as a typical model of the Type I reaction using anti-dinitrophenylated ascaris . IgE serum was significantly inhibited by the oral administration of the following drugs: Aqueous extracts: Aurantii F.i., Bupleuri R., Schizandrae F., Scutellariae R., Zizyphi F., and Shohsaiko-to and Methanolic extracts: Asiasari R., Aurantii F.i., Bupleuri R., Ginseng R., Glycyrrhizae R., Magnoliae C., Schizandrae F. and Trichosanthis S., Contact dermatitis in mice as a model of the Type IV reaction caused by picryl chloride was significantly inhibited by the oral application of aqueous extracts of Ginseng R. and Magnoliae C. as well as the powder of Hoelen. The aqueous extract of Saiboku-to also showed an inhibition of the contact dermatitis, and it significantly potentiated the inhibition of contact dermatitis by prednisolone.