Direct counts of anaphases and telophases in normal human epidermis and in epidermis undergoing forced regeneration after tape stripping show that at least 1/2 of the mitotic axes are oriented vertical to the skin surface, only 1/3 or less parallel to the surface. Mitosis appears to be directly related to the movement of cells out of the basal layer in a high percentage of cases. Upward migration of individual cells independent of mitosis can be recognized during forced regeneration and probably also occurs under normal conditions. Comparison of our results with those of Greulich on mouse esophagus suggests that individual cell behavior in the renewal of stratified squamous epithelia may vary in different tissues and perhaps in different species.