A reproducible technique is described for doubling the length of a loop of small intestine, while simultaneously reducing its luminal diameter, and preserving the maximum amount of small bowel mucosa for intestinal adaptation. In pig experiments, 7 loops have been increased in length by the "intestinal loop lengthening" procedure, with survival of 5 of the 7 animals for a period of 16-26 wk. Leakage from the lengthened intestinal segment led to the death of one animal. At a second operation, or at termination of the experiment, all seven lengthened loops had a good blood supply and were patent along their full length. Histologic examination of 3 of the 4 specimens from the first phase of the study confirmed their viability. The potential application of intestinal loop lengthening in the management of the short gut syndrome is discussed.