Hepatocyte growth factor (HGF), otherwise known as scatter factor (SF), is a recently identified cytokine which exerts a wide spectrum of biological functions on a variety of cell types. Its receptor is encoded by the c-met proto-oncogene. HGF/SF has been implicated in the regulation of mitogenesis, motogenesis, and morphogenesis. Over the past few years, the structure, function and signal transduction pathways of HGF/SF and its receptor have become clearer. The cytokine is now known to play important roles in the regulation of both normal physiological processes as well as pathological ones. This review summarises recent progress involving HGF/SF and its receptor and discusses their role in cell biology, organ regeneration, cancer and other processes. Hepatocyte growth factor (HGF) is a pleiotropic growth factor originally identified as a potent mitogen agent for rat hepatocytes. Subsequent studies have shown that it is mitogenic for a wide range of epithelial cells and not limited to hepatocytes. Its behaviour as a motogenic stimulator promoted its independent discovery and naming of scatter factor (SF). Analysis of cDNA and amino acid sequences have revealed that the two molecules are the same. A number of cytokine agents are known to stimulate cellular motility, however, it is the function of HGF/SF as a potent motogenic, mitogenic and morpho-regulatory agent on the diverse variety of cell types that makes the discovery of HGF/SF factor one of the most interesting stories in terms of identification of novel cytokines.