An immunohistochemical study of 63 cases of uterine cervical cancer was undertaken. It was confirmed that the biological character of the cancer cells derived from the reserve cells changed over the course of invasion. Squamous cell carcinoma had positive keratin antibodies such as CK 10/13 (DE-K 13), CK 14 (NCL-LL 002) and CK 7 (OV-TL 12/30). In invasive squamous cell carcinoma, CK 14 positive cells were piled up and tended to be stained positive by PCNA and laminin. There were two types of staining, one of which revealed CK 14 strongly positive, and the other weakly positive. The first type differed from the second in depth and localization. The cells on the margin of a cluster of cancer cells were stained positive with CK 14 as in normal basal cells. The results obtained suggested: 1) squamous cell carcinoma has not only the character of normal squamous cells, but also that of the cells derived from the cervical glands. 2) cancer cells may develop in accordance with the character of basal cells, and the patterns of invasion change according to the character of basal cells in cancer tissue. (J Nippon Med Sch 1998 ; 14-27)