This paper was presented at the first annual scientific meeting of The Gerontological Society, Inc. on invitation of the program committee as a part of a symposium on the biochemistry and physiology of the aging process. Regeneration of senile human skin can be effected by the topical application of sex hormones Dr. J. Goldzieher has found. Using estrogen in an ointment base the skin of the senile women showed regeneration whereas that of the senile men did not. However, biopsies showed that when either androgen or estrogen was sprayed on the skin in sufficient concentrations regeneration of the skin occurred regardless of sex.