Background: Hepatocyte growth factor (HGF) plays diverse roles in organ development, tissue regeneration, and tumor progression. Measurement of HGF concentrations in blood and tissues using enzyme-linked immunosorbent assay (ELISA) is a simple and easy way to understand the significance of HGF in tissue regeneration, pathophysiology, and diagnosis. Methods: We evaluated 3 ELISA kits from different sources, referred to herein as kits A, B, and C for convenience. Results: We found that the concentrations of human HGF determined using ELISA vary significantly depending on the source of the ELISA kit. Kits A and B detected both single-chain pro-HGF and 2-chain mature HGF, but kit C detected only 2-chain HGF. A difference in reactivity was also detected during analysis of plasma samples. When rat plasma collected 4 h after subcutaneous administration of human HGF was analyzed, the HGF concentration determined using kit B was remarkably higher than those obtained using kits A and C. Results of a biological assay and Western blot analysis indicated that kit B detects even degraded HGF, by which the HGF concentrations determined using kit B were significantly overestimated. Conclusions: This information serves as a guide for the selection of ELISA kits for human HGF. (C) 2008 Elsevier B.V. All rights reserved.