Ten outbred pigs were each operated on for three times. First, a 130 cm length of terminal ileum of each pig was isolated on its vascular pedicle as a Thirty-Vella loop. One week later, the solitary ileal segments were transplanted heterotopically in two pigs. And after 28 days of heterotopic transplantation, the transplanted intestine was interposed into continuity of host intestine as orthotopic transplant. During the experiment, tests were made on 6th day after the first operation (period I), the 14th (II), 28th (III) day after heterotopic transplantation, and 3 weeks after interposition (IV) respectively for the levels of glucose, palmitate and leucine. Additionally, at period I, III, and IV, a 3 cm length of intestinal mucosa was excised for morphologic observation and determination of DNA, RNA and protein contents. After heterotopic transplantation, the absorptive function of transplanted intestine was severely impaired for two weeks. The absorption of glucose and palmitate was partially recovered by period III, at which time leucine level had return to normal. At period IV, the absorptive function of glucose and leucine had surpassed normal levels, while palmitate had risen to the level of pretransplantation. After transplantation, at period III, DNA, RNA and protein contents were well below normal. Three weeks after orthotopic transplantation, RNA and protein had risen to normal level, while DNA content remained below normal. The morphologic changes during the experiment were correlated with the changes of contents in RNA, protein and DNA.(ABSTRACT TRUNCATED AT 250 WORDS)