As many crude drugs are used in the oriental medical field problems on the side effects of these drugs come to the front. To conduct delayed-type hypersensitivity we selected 29 kinds of drugs used frequently for therapeutic agents in oriental medical hospitals (Table I). The cell-mediated immune response was evaluated by measuring the foot pad swelling reaction and humoral immune response by measuring the antibody formation to these crude drugs. Mice were given these drugs intraperioneally for sensitization and challenged with same drug as used for sensitization respectively by intral dermal injection on the left and righ hind foot pad 4 days after senstization and then the foot pads were measured with the dial micrometer. The results were as follow; 1) Gentianae Scabrae Radix, Arecae Semen, Corydalis Tuber, and Paeoniae Radix were significant as delayed-type hypersensitivity inducers. 2) None of the crude drugs tested had effect on the induction of humoral immune response.