This study evaluates the presence of Langerhans’ cells and expression of L1 antigen in squamous epithelium of the normal and dysplastic transformation zone of the cervix uteri and determines the influence of tobacco smoking and pregnancy. Women who smoked and pregnant women showed a decrease of Langerhans’ cell counts in normal epithelium. In cervical intraepithelial neoplasia (CIN) 1 lesions, decreased Langerhans’ cell counts were noted. L1 antigen expression was significantly less in CIN of all grades. Normal squamous epithelium of smokers showed weaker staining for L1 antigen but total staining scores were not significantly different. These data suggest a decrease in epithelial cell-mediated immune response in smokers, pregnant women and in low-grade CIN. Dysplastic squamous cells probably have intracellular regulatory problems independent of other immune cells.