Recently, several epidemiologic observations have suggested that obesity might be an independent risk factor for certain malignancies such as breast cancer, colon cancer, renal cell carcinoma, and esophageal adenocarcinoma. However, there are no studies examining the risk of hepatocellular carcinoma (HCC) in obesity. The aim of the present study was to determine whether obesity is an independent risk factor for HCC in patients with cirrhosis. Explanted liver specimens from a national database on patients undergoing liver transplantation were examined for HCC, and the incidence was compared among patients with varying body mass indices according to the etiology of cirrhosis. A multivariate analysis was used for controlling other potentially confounding variables such as age and sex. Among 19,271 evaluable patients, the overall incidence of HCC was 3.4% (n = 659) with a slightly higher prevalence among obese patients compared with lean patients. Obesity was an independent predictor for HCC in patients with alcoholic cirrhosis (odds ratio [OR], 3.2; 95% CI, 1.5-6.6; P =.002) and cryptogenic cirrhosis (OR, 11.1; 95% CI, 1.5-87.4; P =.02). Obesity was not an independent predictor in patients with hepatitis C, hepatitis B, primary biliary cirrhosis, and autoimmune hepatitis. The higher risk of HCC in obese patients is confined to alcoholic liver disease and cryptogenic cirrhosis. In conclusion, more frequent surveillance for HCC may be warranted in obese patients with alcoholic and cryptogenic cirrhosis. However, as this study is based on patients with advanced cirrhosis, our findings need to be confirmed in a broader population of individuals with cirrhosis.