Hepatocyte growth factor (HGF) facilitates recovery from tissue injuries. We previously reported that serum HGF levels were elevated in chronic renal failure (CRF) patients. In the present study Western blot analysis of CRF patients’ sera showed the majority of their serum HGF was a single-chain precursor molecule. In CRF rats developed by 5/6 nephrectomy or high adenine diet, both HGF mRNA expression levels and tissue HGF concentrations were increased in liver and spleen. The results suggest that HGF production increases in CRF, which may be a response to chronic progressive renal injuries in an endocrine manne