Several candidate tumor markers for cervical neoplasia have been identified. Among those are keratin markers, whose precise implications in the diagnosis are still under debate. In the present study, we aimed to clarify the usefulness of studying the expression of keratins 8, 10, 13, and 17 for diagnostic purposes in human cervix carcinomas. Forty-four invasive squamous carcinomas, 10 cervical intraepithelial neoplasia grade III (CIN III), and 10 reference cervix were examined immunohistochemically with monoclonal antibodies. Expression of keratins in reference exocervix, CIN III, and invasive carcinomas was as follows: keratin 8--0, 44.4%, and 57.1%, respectively; keratin 10-77.8%, 40%, and 19%, respectively; keratin 13--100%, 22.2%, and 25%, respectively; keratin 17-0, 40%, and 73.2%, respectively. In invasive carcinomas, expression of keratin 10 was significantly associated with keratinizing carcinomas. In conclusion, we observed that expression of keratins 8 and 17 and loss of keratins 10 and 13 are good markers of malignant transformation in human cervix. Keratin expression patterns, namely expression of keratin 10, can be useful for subtyping and grading squamous cell carcinomas of the cervix.