215 Background: WHO or RECIST has been considered as suboptimal methods for tumor response assessment in HCC, especially receiving locoregional therapies. Recently, new modified methods having concept of viable tumor has been proposed. Herein we compared the efficacy to assess response and to predict prognosis between WHO, RECIST, EASL, mRECIST in HCC patients receiving TACE. Methods: We retrospectively reviewed 141 HCC patients who were newly diagnosed and received TACE between August 2005 and November 2006. Among them, 98 patients who were available for assessing treatment response were analyzed at 1 month after 2nd TACE. We evaluated intermethod aggreement between methods and assessed the efficacy predicting time to progression (TTP) and overall survival (OS). Results: The results of tumor responses (number of CR/ PR/ SD/ PD) by WHO/ RECIST/ EASL/ mRECIST were 1/ 14/ 74/ 9, 1/ 12/ 77/ 8, 34/ 34/ 25/ 5, 34/ 28/ 31/ 5, respectively. The κvalue of intermethod agreement for EASL vs WHO, EASL vs RECIST, mRECIST vs WHO, and mRECIST vs RECIST was 0.102, 0.088, 0.112 and 0.122, respectively. The κvalue for WHO vs RECIST and EASL vs mRECIST was 0.759 and 0.883 (p=0.00). Hazard ratios for TTP in responders compared with nonresponders were 0.313 (95% CI; 0.19-0.52, p=0.00) for EASL and 0.335 (95% CI; 0.21-0.54, p=0.00) for mRECIST. Hazard ratios for survival in responders compared with nonresponders were 0.208 (95% CI; 0.12-0.37, p=0.00) for EASL and 0.269 (95% CI; 0.15-0.48, p=0.00) for mRECIST. In the univariate analysis, tumor size, infiltrative type, PVT, EASL responder, and mRECIST responder were significant risk factors for survival. Multivariate analysis showed EASL responder (HR 0.165, 95% CI 0.056-0.486, p=0.001) and infiltrative type (HR 4.504, 95% CI 1.579-12.848, p=0.005) were independent predictable factors for survival. Conclusions: The recent proposed methods showed different characteristics from preexisting methods in assessing treatment response and furthermore, responder by EASL method was independent predictor for survival in HCC patients receiving TACE. EASL method should be applied as response assessment method for HCC patients receiving TACE. No significant financial relationships to disclose.