Obesity and the metabolic syndrome (MS) are growing epidemics associated with an increased risk for many types of cancer. In the liver, inflammatory and angiogenic changes due to insulin resistance and fatty liver disease are associated with an increased incidence of liver cancer. Regardless of underlying liver disease, cirrhosis remains the most important risk factor for hepatocellular carcinoma (HCC) although rare cases of HCC arising without cirrhosis raise the possibility of a direct carcinogenesis secondary to nonalcoholic fatty liver disease (NAFLD). Moreover, MS and its different features may also increase the risk of HCC in the setting of chronic liver diseases of other causes such as viral hepatitis or alcohol abuse. Taking into account all these data, it is necessary to better determine the risk of developing HCC in patients with MS to improve the screening guidelines and develop prophylactic treatments in this setting.