The percentage of ciliated cells, the height, and the mitotic index of human oviductal epithelium were studied during the menstrual cycle and under progestogens. A total of 141 fallopian tubes were examined. During the menstrual cycle, a process of ciliation and deciliation was observed. Maximal ciliation was attained around the time of ovulation, particularly in the fimbria where significant differences were noted. Deciliation was observed under progestogen therapy, but this progestogen effect was easily reversible. The decrease of epithelial height observed after ovulation was also found after progestogen therapy. Cyclic mitotic activity was noted during the menstrual cycle. Estrogens influence the mitotic activity of tubal epithelium, whereas endogenous progesterone and progestogens inhibit this estrogenic effect.