Hepatocyte growth factor (HGF)/scatter factor (SF) is a multifunctional factor considered to be potentially involved in tissue regeneration, wound healing, embryogenesis, angiogenesis and cancer invasion. Here we examined immunohistochemically the distribution of HGF/SF in human tissues, including cancerous and inflammatory tissues, using anti-HGF antibody. HGF/SF accumulation was clearly detected in the extracellular matrix, particularly along the basement membrane, in cancerous and inflammatory tissues, but only a little was detected in normal tissues. HGF/SF is well known to have a strong affinity for heparin in vitro, and from the results of our immunohistochemical assay, we considered that HGF/SF was bound to heparin or heparan sulfate of the extracellular matrix and basement membrane. HGF/SF was well localized in cancerous and inflammatory lesions of human lung, liver and pancreas, and in apparently normal tissues of kidney, adrenal gland and pancreas obtained at autopsy. In lung, HGF/SF was localized along the basement membranes of cancer cell nests, in the extracellular matrix of the cancer cell surface, cancer stroma and tissues invaded by cancer, and the basement membranes of bronchial epithelium and capillary vessels in inflammatory stroma. Since HGF/SF makes some cancer cells more invasive in vitro, the accumulation of HGF/SF in cancerous tissue suggests that the invasiveness of some cancer cells may be increased by HGF/SF in vivo.