Performance status is included in the Barcelona Clinic Liver Cancer (BCLC) system for hepatocellular carcinoma (HCC). Few studies specifically evaluated the role of performance status in patients with HCC. This study investigated its distribution, determinants, and prognostic impact, aiming to improve the performance of the BCLC system. A total of 2,381 HCC patients were enrolled. Performance status was determined according to the Eastern Cooperative Oncology Group scale. The prognostic ability of the original and three modified BCLC systems in HCC patients was compared by the Akaike information criterion (AIC). There were 60, 17, 11, 8, and 4% of patients who were classified as performance status 0, 1, 2, 3, and 4, respectively. A worse performance status significantly correlated with age, alcoholism, hypoalbuminemia, hyperbilirubinemia, renal insufficiency, hyponatremia, and prothrombin time prolongation (all P < 0.001). Larger tumor burden, poorer residual liver function, more frequent vascular invasion, and diabetes mellitus were also observed in patients with worse performance status (all P < 0.001). Patients with poorer performance status more often received best supportive care (P < 0.001). In the Cox proportional hazards model, performance status was an independent prognostic predictor and the long-term survival tended to be worse in patients with progressively poor performance status (all P < 0.05). Reassigning patients with performance status 0 or 1 to stage B provided the lowest AIC among the four BCLC-based staging systems. Conclusion: Performance status is strongly associated with both tumoral and cirrhotic factors and accurately predicts long-term survival in HCC patients. Modification of the BCLC system based on performance status may further enhance its prognostic ability in patients with early to advanced cancer stage. (HEPATOLOGY 2013;57:112-119) H epatocellular carcinoma (HCC) is a major malignancy worldwide and increasing incidence of HCC has been observed.1,2 The majority of symptomatic HCC patients are diagnosed at an intermediate or advanced stage, 3 and curative treatments (resection, transplantation, and local ablation) are unlikely to be perform because of extensive tumor invasion, decompensated liver function, or poor general condition.The performance status scale developed by the Eastern Cooperative Oncology Group (ECOG) is recorded from 0 (fully active, able to carry on all predisease performance without restriction) to 5 (dead).4 These criteria and scales are extensively used by physicians to