Aims: We investigated whether baseline inflammation and immune- based scores predict prognosis of hepatocellular carcinoma (HCC) patients treated with transarterial chemoembolization (TACE). Methods: A total of 615 consecutive patients with HCC who had undergone TACE as initial treatment were included from a prospective cohort. The systemic immune inflammation index (SII) defined as (platelet count × neutrophil)/lymphocyte, neutrophil-lymphocyte ratio (NLR), platelet-lymphocyte ratio (PLR) were analyzed with regard to their associations with disease progression and survival. Results: All of the tested inflammation/immune-based scores were significantly associated with overall survival in the univariate analysis. In the multivariate analyses, SII levels were independent risk factors for poorer survival together with BCLC stage, serum AFP levels, maximum tumor size, and Child-Pugh score. The hazard ratio of death for each increase in SII level was 3.483 (95% confidence interval, 1.971-6.156; p<0.001). Furthermore, SII significantly improved discrimination function of BCLC stage in predicting overall survival. Conclusions: High baseline SII independently correlated with poorer OS in patients with HCC who underwent TACE.