Patch testing with Dermatophagoides antigens, mite antigens, and fecal antigens of mites was performed on 34 cases of atopic dermatitis of the adult type. The fecal antigens induced positive reactions more frequently than mice antigens in patients with higher scores of IgE RAST (score 4). Histologically, the positive reaction showed mild perivascular infiltration of lymphocytes and edema in the papillary dermis at 24 hours after the patch test. The lymphocytic infiltration became more prominent and was intermingled by eosinophils at 48 hours. The epidermis showed mild intercellular edema. Eosinophils and lymphocytes infiltrated into the epidermis to form spongiotic bulla at 72 hours.