Appropriate patient selection is crucial in ensuring acceptable outcomes from orthotopic liver transplantation (OLT) for hepatocellular carcinoma (HCC). The United Network for Organ Sharing (UNOS) has elected to prioritize HCC patients for OLT based on criteria of tumor burden. However, it is unclear whether these criteria correlate with outcome, or with the pathobiological features associated with tumor recurrence. Therefore, we analyzed 109 consecutive patients undergoing OLT for HCC at our center, to determine the utility of present selection criteria in predicting outcome. Pathologic tumor staging of the explanted liver was based on the American Tumor Study Group modified tumor node metastases (pTNM) classification system. Multifocality was defined as >4 tumor nodules on explant. Survival analysis was performed using Kaplan-Meier and Cox proportional hazards regression methods. At a median follow-up of 18.9 months, the overall mortality was 19% with 15 patients (14%) dying of recurrent HCC. Kaplan-Meier 1, 3 and 5-year survival rates were 89.5%, 68%, and 65%, respectively. Recurrence-free rates of 1, 3, and 5 years were 89%, 75%, and 65%, respectively. On univariate analysis, the factors found to be significantly associated with recurrence of HCC were explant features of macrovascular invasion, tumor size (per centimeter increase), pTNM stage (per 1-stage increase), and pre-transplant serum alphafetoprotein (AFP) >300 ng/mL. In defining a threshold level, we found that explant tumor diameter >3 cm, and those tumors classified as at least pT3 on pathological examination, were significantly associated with recurrence (P โซุโฌ .01 and .03, respectively). Tumor size on explant was found to be strongly correlated with multifocality (P โซุโฌ .017) and vascular invasion (P โซุโฌ .02). Patients exceeding pathological UNOS criteria were 3.1 times more likely to have recurrence of HCC (P โซุโฌ .03). In conclusion, we found that tumor size appears to be a surrogate marker for negative pathobiological predictors of outcome, i.e., vascular invasion and multifocality. Present UNOS selection criteria for HCC based on tumor burden appear to provide adequate discriminatory power in predicting outcome of OLT. (Liver