Experimental studies have shown that N(3',4'-dimethoxycinnamoyl) anthranilic acid (Tranilast) inhibits reaginic antibody-mediated hypersensitivity reactions, and it has been demonstrated to be an effective drug for patients with bronchial asthma. On the other hand, from the nature of the cellular infiltrate seen in eczematous lesions, it appears that some form of cell-mediated immunity may be involved in addition to IgE-mediated immunity in the pathogenesis of atopic dermatitis (AD). Moreover, we have previously reported that the proliferative responses of peripheral blood mononuclear cells (PBMCs) to ovalbumin (OA) or bovine serum albumin (BSA) in children with AD who are sensitive to hen's egg or cow's milk were significantly higher than those of healthy children and hen's egg or cow's milk sensitive children with immediate symptoms. In this study, we have showed that the proliferative responses of PBMCs to OA were dose-dependently inhibited by Tranilast on patients with AD. The responding cells to OA were shown, through separation experiments, to be T cells, and the proliferative responses of T cells to OA were also dose-dependently inhibited by Tranilast. Moreover, the inhibition was thought to occur at the initial stage of the proliferative reactions. These results suggest that Tranilast can be clinically applied to patients with AD.