Measurements of normal intestinal length in preterm infants is necessary in planning postoperative management following major bowel resection for necrotizing enterocolitis and other surgical conditions. A prospective autopsy study of 30 stillborn and newborn infants varying in gestational age from 19 to 40 weeks was undertaken to correlate gestational age with measurements of intact small intestine and colon. Only cases falling between the 10th and 90th percentile for body weight on the intrauterine growth curve were included. Mesenteric attachments were divided and intestine measured along the unstretched antimesenteric margin. Overall intestinal length for infants between 19 and 27 weeks gestation increased from 142 +/- 22 cm (mean +/- S.D.) to 304 +/- 44 cm for a comparable group over 35 weeks gestation. Knowing that jejunum, ileum, and colon more than double in length during latter gestation may have value in estimating prognosis and planning treatment for many preterm "short-gut" patients previously considered to have inadequate remaining intestine for survival.