Human hepatocyte growth factor (hHGF) has considerable sequence homology with plasminogen and both proteins can be activated by plasminogen activators. The aim of this study was to investigate the relationship between plasma hHGF and fibrinolysis in patients with fulminant hepatic failure (FHF), in whom proteases of coagulation are known to be activated and hHGF levels have been shown to be raised as a consequence of hepatic regeneration. Serum hHGF measured by ELISA was increased in FHF (median 6.67 ng/ml, range 1.2-62 ng/ml), but the values did not correlate with the decreased plasminogen level (median 9%., range 0.7-35.5%) or the level of t-PA which was normal. There was a significant correlation between serum hHGF and increased plasma D-dimer (median 2,163 microgram/l, range 39-7 311 microgram/l), produced by the action of plasmin on fibrin and increased plasma thrombin-antithrombin III complexes (TAT, median 31.7 microgram/l, range 3.7-105 microgram/l). These relationship could be indicative of an involvement of blood coagulation, possibly a specific serine protease, in hHGF activity. After liver transplantation, plasma hHGF was rapidly cleared to almost normal levels, whereas D-dimer and TAT continued to be at elevated levels.