Cytokeratins of normal epithelia and of some neoplasms of the female genital tract were studied by immunofluorescence microscopy of frozen sections and by two-dimensional gel electrophoresis of cytoskeletal proteins from microdissected tissues. All normal epithelia were stained with the monoclonal cytokeratin antibody KG 8.13 whereas certain monoclonal antibodies stained only simple epithelia. As revealed by gel electrophoresis the normal epithelia of the ovarian surface, oviduct, endometrium and endocervix contained cytokeratin polypeptides Nos. 7, 8, 18 and 19. In contrast, stratified exocervical epithelium showed a much more complex pattern (polypeptides No. 1, 2, 4, 5, 6, 11, 13, 14, 15, 16, 17 and 19). A similar pattern was found in the vagina. All epithelial neoplasms studied, regardless of the degree of histologic differentiation, were stained with antibody KG 8.13 as well as with conventionally obtained guinea pig antibodies to bovine muzzle prekeratins. The ovarian, endometrial and endocervical epithelial tumors maintained the pattern of their cells of origin, i.e. they expressed only cytokeratins Nos. 7, 8, 18 and 19. In one type of endocervical adenocarcinoma an additional cytokeratin polypeptide (No. 17) was detected. In contrast, the epithelial tumors of the lower genital tract showed a more complex pattern which also showed some differences with respect to that described for the corresponding normal tissue. Thus, in non-keratinizing squamous cell cervical carcinomas, cytokeratins Nos. 5, 6, 7, 8, 13, 14, 15, 16, 17, 18 and 19 were present, whereas the keratinizing cervical cancers showed polypeptides Nos. 5, 6, 13, 14, 16, 17 and 19.(ABSTRACT TRUNCATED AT 250 WORDS)