Recently pathotoxicological study of lymphoid organs by administration of some phthalate ester in rats, indicated marked effect of architechure of thymus, spleen, and lymphonodes. Dioctyl phthalate (DOP), one of the phthalate ester, caused statistically significant reduction in the weights of various lymphoid organs. This senstivity of the lymphoid organ to phthalate toxicity which could lead to adverse effects on the immune response and also suppression of immune system. Therfore it is possible the presense of di-(2-ethylhexyl) phthalate (DEHP), one of the phthalate ester as well as DOP, in spleen and other organs might have some moderately effect on the function of the immune system, So our present study was proceeded to assess the effect of DEHP on the immunotoxicity in mouse. In the immune response of DEHP administered mice, HA, HY, Arthus reaction and Rosette forming cell were decreased but DTH was increased. Furthermore, in the DEHP plus ethanol group, HA, HY, Arthus reaction and Rosette forming cell were remarkably decreased and elevation of DTH was inhibited.