The natural history of Non Alcoholic Fatty Liver Disease (NAFLD) is difficult to assess, but there is mounting evidence that patients with NAFLD may eventually develop cirrhosis and hepatocellular carcinoma (HCC). Retrospective, case-control studies have shown that features suggestive of Non Alcoholic SteatoHepatitis (NASH) are more frequent in HepatoCellular Carcinoma (HCC) complicating cryptogenic cirrhosis than in matched HCC patients with known etiology. In the only available prospective cohort study, there is the absence of HCC as a complication of NASH-associated cirrhosis after a mean follow up of 7 years (median 5 years). However prospective NASH studies are too short to exclude late complications. In fact the average lenght of cirrhosis before the diagnosis of HCC was 16 years. The prevalence of risk factors associated with NASH can account for the increasing incidence of cryptogenic cirrhosis and subsequent HCC. Obesity and diabetes per se are significantly associated with the development of HCC. In particular diabetes was found to be a risk factor for HCC independent of age, gender, and race. Chronic hyperinsulinaemia and insulin-like growth factor 1 (IGF-1) might be involved in hepato-carcinogenesis. Exposure to physiological insulin concentrations stimulate proliferation of human and rat hepatoma cell line. Changes in the expression pattern of IGF-system components has been observed in patients with HCC, in human hepatoma cell lines and in their conditioned culture medium.