Because of improvements in supportive care, many infants now survive massive intestinal loss and have short bowel syndrome. Unfortunately, some survivors are left with an insufficient amount of intestine and cannot be weaned from total parenteral nutrition. An isoperistaltic intestinal lengthening procedure was used to treat surgically two such infants with 25 centimeters of remaining small intestine and absent ileocecal valves. This surgical technique longitudinally divides the short, dilated small intestine into two smaller, parallel lumens that are anastomosed end to end. This procedure preserves all mucosa, prolongs transit time by doubling intestinal length and corrects the ineffective peristalsis by tapering the dilated intestine. The lengthening technique can be performed because of the anatomic division of the intestinal vasculature within two leaves of the mesentery. Longitudinal division between the two leaves maintains vasculature to each side of the intestine. The isoperistaltic intestinal lengthening procedure, as it was successfully applied to two infants, is described in detail.