Immunoreactivity with monoclonal antibodies against epithelial membrane antigen (EMA), vimentin, squamous epithelium-specific keratin, nonsquamous epithelium-specific keratin, and polyclonal antibodies epithelial cells of 55 cervical smears using the avidin-biotin-peroxidase complex and indirect immunoperoxidase methods to detect antigens. Most of the abnormal squamous cells with few normal cells were reactive for EMA but the intensity of the reaction was variable in both cases. There was no correlation in the reactivity between normal and abnormal cells with different cytokeratins varying in their molecular weight. Vimentin was also reactive with both cells. The results of this experiment suggest that antibodies used, appear to be of limited usefulness in the diagnosis of cervical smears.