Thirty-one cervical carcinomas have been studied immunohistochemically to determine tumor growth fraction by using the monoclonal antibody Ki-67, which reacts with a nuclear antigen expressed only by proliferating cells. The growth fraction of individual tumor is estimated as the percentage of stained nuclei in a population of 1000 tumor cells. There is a good correlation of the growth fraction measured by Ki-67 with mitotic index and high histological grade of cervical carcinoma. This study, together with that of D. C. Brown, D. Cole, K. C. Gatter, and D. Y. Mason [Brit. J. Cancer 57(2), 178-181 (1988)], shows the usefulness of Ki-67 in the evaluation of growth fraction in cervical carcinoma.