This study was concerned with the cellular growth of muscle tissue in rats during the early stages of recovery from undernutrition. Groups of animals were undernourished either pre- or post-weaning and realimentated on either unrestricted intakes or on a restricted intake regime Rates of increase in body mass were highest on both dietary treatments in animals undernourished after weaning. On unrestricted intakes these animals also had the most rapid multiplication of muscle “cells” but their rate of increase in muscle “cell size” was low. Patterns of increase in muscle components during realimentation on the restricted intake regime were related to differences in potential for growth between groups.