I was very interested by Dr. Wegman's article on vital statistics (Pediatrics 58:793, December 1976). Nevertheless, I would like to share some reservations that I have concerning the inference he made regarding the decrease in neonatal mortality: "The steady decline in the neonatal mortality rate, almost as rapid as that of the post-neonatal rate, does imply that care of the neonate has improved." I would like to review the definition of neonatal mortality, enumerate some of the factors influencing it, and cite examples of the importance of those factors.