In order to investigate the type of infiltrating T cells in allergic contact dermatitis (ACD) reaction, by the methods of RT-PCR and immunohistochemistry, we tried to detect IL-2mRNA, IL-2, IFN-?, IL-4 in the lesions of patients with ACD. The results showed that Th1 cytokines were expressed aberrantly in ACD patients and Th1-like clone which secrets IL-2, IFN-? appeared to be predominant in ACD reaction.