We examined the changes in serum human hepatocyte growth factor (hHGF), also called "scatter factor," levels after transcatheter arterial embolization (TAE) and partial hepatectomy (PH) in patients with hepatocellular carcinoma and metastatic liver tumor. In most cases, the serum hHGF levels increased transiently 1-3 days after TAE or PH, and then decreased nearly to the basal levels in 1 wk, suggesting that hHGF may play an important role in liver regeneration in humans. The mean amount of increase in serum hHGF levels after PH was 0.38 ng/ml, which was greater than that after TAE (0.16 ng/ml). In three cases of TAE followed by PH, two showed a greater increase in serum hHGF levels with PH than with TAE, but the third showed the reverse result. Because the rate of increase in serum ALT levels did not affect that of serum hHGF levels, the degree of liver injury induced by TAE or PH does not seem to be a determinant in serum hHGF elevation.