The serum levels of hepatocyte growth factor (HGF) were determined in patients with various renal diseases. In patients with acute-phase acute renal failure (ARF) and chronic tubulointerstitial nephritis (chronic TIN), the serum HGF levels were 0.55 ± 0.24 and 0.44 ± 0.37 ng/ml (mean ± SD), respectively, and were significantly higher than that in the control group (0.12 ± 0.12 ng/ml). The serum HGF level tended to be high also in patients with active-phase steroid-sensitive nephrotic syndrome (SSNS). The serum levels of HGF were not elevated in patients with IgA nephropathy (IgAN), Henoch-Schönlein purpura nephritis (HSPN), membranoproliferative glomerulonephritis (MPGN), poststreptococcal acute glomerulonephritis (PSAGN), unilateral renal atrophy, unilateral nephrectomy, or proximal tubular dysfunction. These observations suggest that glomerular disorders cause no apparent elevation of the serum HGF level, and that elevation of the serum HGF level may be associated with tubulointerstitial damage in renal diseases.