The location of transferrin receptor (Tf.R) which is abundantly contained in proliferating cells and positional relationships of cells containing much Tf.R was observed on cervical and endometrial tissue sections by immunohistochemistry. In normal squamous epithelium, the parabasal cell layer was positive and the basal, intermediate, and superficial cell layers negative. This shows that the cells of the parabasal cell layer are proliferating most actively among those layers. Squamous carcinoma contained many positive cancer cells. But negative as well as positive cells were present, indicating that cancer cells proliferate under various conditions. Cancer cells infiltrating the stroma were made clear by Tf.R staining, and it became easier to identify them when only a few were present. Endometrial glandular cells in the basal layer stained only on the basal side of a cell regardless of the menstrual cycle, whereas in the functional layer glandular lumen side also stained positive in the secretory phase. Based on the present data, an immunohistochemical study of Tf.R seems useful to confirm the localization of proliferating cells and cancer cells and determine the conditions for cancer cell proliferation on the tissue sections.