The study of a series of 18 cervical intraepithelial neoplasia (CIN) grade II and III was aimed at determining the distribution and phenotype of immunocompetent cells (Langerhans cells, T and NK cells) and the alteration in the expression of EGF receptors and beta 2-microglobulin in correlation with human papillomavirus (HPV) infection (viral antigen and DNA typing with biotinylated probes). These lesions were characterized by a reduced number of Langerhans cells and a dense infiltrate. HPV infection did not induce HLA-DR expression in the infected epithelial cells. We observed an enhanced expression of epidermal growth factor (EGF) receptors by epithelial cells and a reduced beta 2-microglobulin reactivity by both epithelial and immunocompetent cells. Most of CIN showed foci of infected cells. No significant differences were observed in immunological markers of CIN harboring benign HPV 6/11 DNA or oncogenic HPV 16/18 DNA. Viral antigen was not detected in these lesions. These changes in the epithelial cells of CIN and their microenvironment associated to the lack of HLA-DR expression in the infected cells hamper the squamous epithelial cells to function as antigen presenting cells. This may facilitate a decrease in the immunological surveillance and may contribute to the severity of such lesions.