AIM: To elucidate the pre-treatment clinical and imaging findings affecting the tumor response to the transcatheter reatment of unresectable hepatocellular carcinoma (HCC).METHODS: Two hundred cirrhotic patients with HCC received a total of 425 transcatheter treatments. The tumor response was evaluated by helical CT and a massive necrosis (MN) was defined as a necrosis ＞ 90%.Twenty-five clinical and imaging variables were analyzed:uninodular/multinodular HCC, unilobar/bilobar, tumor capsula, hypervascular lesion, portal vein thrombosis,portal hypertension, ascites, platelets count, aspartate transaminases/alanine transaminases (AST/ALT), alfafetoprotein (AFP) ＞ 100, AFP ＞ 400, serum creatinine,virus hepatitis C (VHC) cirrhosis, performance status,age, Okuda stage, Child-Pugg stage, sex, CLIP (Cancer of the Liver Italian Program) score, serum bilirubin,constitutional syndrome, serum albumine, prothrombin activity, BCLC (Barcelona Clinic Liver Cancer) stage.Prognostic factors of response were subjected to univariate analysis and thereafter, when significant, to the multivariate analyses.RESULTS: On imaging analysis, complete response was obtained in 60 (30%) patients, necrosis ＞ 90% in 38(19%) patients, necrosis ＞ 50% in 44 (22%) patients,and necrosis ＜ 50% in 58 (29%) patients. Ninety-eight (49%) of the 200 patients were considered to have a MN. In univariate analysis, significant variables (P ＜0.01) were: uninodular tumor, unilobar, tumor size -6cm, CLIP score ＜ 2, absence of constitutional syndrome,and BCLC stage ＜ 2. In a multivariate analysis, the variables reaching statistical significance were: presence of tumor capsule (P＜0.0001), tumor size 2-6 cm (P ＜ 0.03), CLIP score ＜ 2 (P＜0.006), and absence of constitutional syndrome (P＜0.03). Kaplan-Mayer cumulative survival at 12 mo was 80% at 24 mo was 56%. MN was associated with a longer survival(P ＜0.0001).CONCLUSION: MN after transcatheter treatment is more common in the presence of tumor capsule,maximum diameter of the main lesion between 2 and 6 cm, CLIP score ＜ 2 and absence of constitutional syndrome. The ability to predict which patients will respond to transcatheter treatment may be useful in the clinical decision-making process, and in stratifying the randomization of patients in clinical trials.