Eleven fetuses and 9 newborns were examined for sensory innervation of the anorectal area. The specimens were obtained immediately after death and were stained by the modified Gross silver impregnation method and examined with a light microscope. The perianal skin and rectal mucosa did not differ in either group. The anal canals of the fetuses had numerous thin, singly- and doubly-branched nerve endings with 1.0 to 1.5 m axonal diameters. Paccinian-type lamellated corpuscles were few and contained 3–5 fibroblastic lamellae and had a diameter of 70–100 m. The newborn group had more prominent subepithelial free nerve endings with 2.0 to 2.5-m axonal diameters, mostly myelinated and with numerous Paccinian corpuscles with 8–10 lamellae and diameters of 100–150 m. Globular endings were fewer and smaller in the fetal group. Muscle spindles were seen embedded in the external sphincter muscle bundles of both groups. We conclude that this pattern of sensory nerve endings indicates a time-dependent developmental process in the human anal canal.