AbstractThe c‐met proto‐oncogene encodes the receptor to hepatocyte growth factor‐scatter factor (HGF‐SF), a mesenchyme‐derived cytokine with cell‐dissociating, invasion, and angiogenic properties. The expression of c‐met in breast cancer is the subject of controversy; 111 primary breast cancers were examined for LOH of c‐met by Southern blot electrophoresis. c‐met expression was measured in a further 40 patients with breast cancer and in 8 patients with benign breast disease by flow cytometry. LOH of c‐met was detected in only 4% of informative breast cancers. Expression of c‐met was significantly greater in patients with breast cancer than in those with benign breast disease (P <0.01, Mann‐Whitney). There was no correlation however between increased c‐met expression and clinicopatho‐logical prognostic variables. These results do not support the role of c‐met as a tumour suppressor gene in breast cancer but suggest increased receptor expression in malignant breast disease. The significance of this increased expression in breast cancer is the subject of further investigation. © 1995 Wiley‐Liss, Inc.