Standards for human fetal intestinal length are not well established but have important implications for the care of the preterm and intra-uterine growth-retarded (IUGR) infant. Our purpose was to examine the relationship between intra-uterine growth and intestinal length in the human fetus. One hundred infants were studied. Birth weight and gestational age ranged from 76 to 4,385 g and from 12 to 42 weeks, respectively. Twenty-one infants were noted to be IUGR. Intestinal length (total, small, large) increased (p < 0.0001) with birth weight, gestational age, and crown-heel length but was reduced in IUGR infants. The ratio of body weight to intestinal length increased with gestation but was also reduced in IUGR infants. In conclusion, a reduced functional mass, as suggested by decreased intestinal length or body weight:intestinal length ratio, may contribute to the poor weight sometimes seen in the very-low-birth weight or IUGR infant.