Hepatocyte Growth Factor (HGF)/Scatter Factor (SF) is a secretory glycoprotein from stromal fibroblasts which binds to the transmembrane c-met receptor. This receptor is expressed from a variety of tumors, including gastric carcinomas. To look for a possible paracrine loop between gastric cancer cells and their surrounding fibroblasts in gastric carcinoma, the effect of HGF/SF treatment on the morphology and the expression of cell adhesion molecules was examined. The cell line TMK-1, established from poorly differentiated gastric carcinoma, responded with scattering after HGF/SF treatment. We found that the observed morphological changes were accompanied with a reduced expression of E- and P-cadherin protein in these cells. In a cell line established from well differentiated gastric carcinoma, named MKN-28, neither scattering nor changes in cadherin expression could be detected. This results suggested, that HGF/SF is a regulator of cell adhesion via affecting E- and P-cadherin. Taking into account, that only cells from poorly differentiated gastric carcinoma cell lines responded in scattering after HGF/SF treatment, paracrine secreted HGF/SF may play an important role in the pathogenesis of these type of gastric carcinoma in vivo.