Both hepatic and renal regeneration are associated with rapid increases in hepatocyte growth factor (HGF)mRNA levels, not only in the regenerating tissue, but also in the lung. In this study, changes in the levels of HGF mRNA in the terminal ileum and also in distal organs in the rat following massive small bowel resection (MSBR) have been investigated with a sensitive S1 nuclease assay. HGF mRNA levels are low in the ileum and increase only transiently post-MSBR. In contrast to the other models of regeneration, no increase in HGF mRNA levels is observed in the lung nor in kidney and liver post-MSBR. This suggests that the ileum does not release "injurin", the putative humoral mediator of the response of the lung observed after hepatectomy or nephrectomy.