The purpose of this study was to determine tissue distribution of certain cytokeratins along the ectocervical lining. A series of 20 cases was investigated by immunocytochemical labelling with specific antibodies against cytokeratins 19, 18, 8, 7, 10. Monoclonal antibodies were used on frozen sections. Distribution of keratin or alteration in expression was correlated with morphologic changes. All specimens were lined by a normal stratified squamous epithelium which was devoid of argyrophilic cells. Low molecular weight cytokeratins 8, 18, 19 (normally expressed in simple epithelia) were consistently and exclusively expressed through out the basal cell layer of the ectocervical lining. Some other particular immunostainings have been noted. A peculiar staining pattern was observed around some stromal papillae. Development of papillae was accompanied by the expression of cytokeratin 10 (which is commonly detected in skin), and by a reduction in the level of expression of simple epithelial cytokeratins. In addition, in the middle zone, anticytokeratin 10 revealed a mosaic of positive and negative cells even in light microscopically non keratinizing squamous epithelium, with differences of expression from case to case.