We investigated the localization and the immunoreactivity (IR) of vimentin in normal and cancerous glandular epithelia of the uterine corpus and cervix. The materials for the study were 33 cases of endometrial adenocarcinoma, 21 cases of endocervical adenocarcinoma, and 12 cases of uterine myoma which had normal endometrium and cervix. A similar study was also performed on smear materials. In normal endometrium, the vimentin was localized not only in the stromal cells but also in the epithelial cells. The IR of the vimentin in the epithelial cells was more prominent in the proliferative phase than in the secretory phase. On the other hand, in normal cervix, the vimentin was not localized in the epithelial cells. In endometrial adenocarcinoma, the IR of the vimentin was markedly or moderately positive in more than half of the cases. In endocervical adenocarcinoma, the IR of the vimentin was absent in all but 2 cases which were of the endometrioid type. The vimentin IR of the stromal cells was clearly observed in endocervical as well as endometrial adenocarcinoma. Very similar results were observed in the smear materials. In endometrial adenocarcinoma, the differentiation, the depth of myometrial invasion and the lymph node metastasis were regarded as the prognostic factors, and the vimentin IR appeared more intensive in the cases of well differentiated and superficial myometrial invasion. The above results showed that there was a remarkable difference between endometrial and endocervical epithelial cells in the vimentin IR.(ABSTRACT TRUNCATED AT 250 WORDS)