In a previous study, we showed that the level of soluble CD25 (sCD25) was elevated in a small series of patients with hepatocellular carcinoma (HCC). In the present study, we determined the capacity of serum levels of sCD25 to detect the presence and the early stage of HCC using a larger cohort of HCC patients and evaluated the correlation between sCD25 level and tumor burden. Serum levels of sCD25 were quantified using ELISA in patients with HCC (n=145), controls with advanced fibrosis (n=61) and healthy control subjects (n=30). The levels of sCD25 in patients with HCC (median, 6,955 pg/ml) were significantly higher than those in cirrhosis-only patients (4,310 pg/ml; P<0.0001). At a cut-off value of 2,180 pg/ml, sCD25 had a sensitivity of 92.3% and a specificity of 37.7% in detecting HCC presence [area under the curve (AUC) of 0.685; P<0.0001]. By comparison, α-fetoprotein (AFP) had a sensitivity of 53.8% and a specificity of 86.8% at a cut-off value of 32.8 ng/ml (AUC=0.755; P<0.0001) for HCC presence detection. For early HCC, the sensitivity of sCD25 was 89.6% and its specificity was 39.3% (AUC=0.630; P<0.0001) at a cut-off value of 2,859 pg/ml, while AFP had a sensitivity of 41.7% and a specificity of 82.6% at a cut-off value of 20.6 ng/ml (AUC=0.630; P=0.0257). We also found a significant positive correlation between serum levels of sCD25 and tumor stage. In the present study study, sCD25 was more effective than AFP at detecting the presence and early stages of HCC. This immune factor may hold promise as a novel predictive marker of HCC presence and may be useful in distinguishing early HCC from advanced cirrhosis, currently areas of global unmet need.