Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer and the third leading cause of cancer related death worldwide. In recent years, the prevalence of HCC has increased in both developing and developed countries. Most HCC cases develop in the presence of advanced chronic liver disease related to viral hepatitis. In particular hepatitis B virus and hepatitis C virus infections are considered as major HCC risk factors worldwide. However, current studies provide strong evidence for increasing numbers of HCC in nonalcoholic fatty liver disease (NAFLD). NAFLD represents the hepatic manifestation of metabolic syndrome which is based on obesity and insulin resistance. Epidemiologic data clearly demonstrates that NAFLD and obesity-related disorders are significant risk factors for tumor development in general and HCC in particular. As a consequence of life style changes towards higher calorie intake and less exercise, obesity and metabolic syndrome are spreading all over the world. Due to this increase in obesity and metabolic syndrome NAFLD-related HCC will become a major health care problem in the future. In conclusion, better understanding of the impact of NAFLD and obesity in the development of HCC will improve our treatment strategies of HCC and allow preventive measures.