The question 'Why hepatocellular carcinoma cells are unlikely to metastasize although they have a high proliferative activity?' is a major point of interest from a cancer physiopathological viewpoint. Recent articles about the roles and relationships of some cytokines with matrix degrading enzymes and their inhibitors in various types of normal tissues and malignancies give rise to another question: 'Does tissue inhibitor of metalloproteinase-1 prevent the extrahepatic metastasis of hepatocellular carcinoma cells?' On the basis of many evidences, it is highly probable that under the effect of a possible inducing mechanism of the cytokines interleukin-6, -1 beta and transforming growth factor beta, the increase in concentration of tissue inhibitor of metalloproteinase-1 in hepatocellular carcinoma cause increased type I collagen accumulation and consequent prevention of cellular detachment, which explains why highly proliferative malignant hepatocytes have less metastatic ability. (C) 2001 Harcourt Publishers Ltd.