Aberrant metabolisms have been hypothesized to precede the occurrence of hepatocellular carcinoma (HCC), therefore, we investigated biomarkers associated with subsequent HCC in peripheral bloods using metabolomic technologies. A cohort of 475 HCC-naïve liver cirrhotic patients were recruited and prospectively followed. A total of 39 patients developed HCC in the follow-up period. Baseline plasma metabolites were explored using untargeted nuclear magnetic resonance. Candidates were then quantified by ultra-performance liquid chromatography. A series of univairiate and multivariate analysis showed that Phenylalanine (Phe) and Glutamine (Gln) levels are associated with time to HCC, independent of viological etiologies and age. A HCC risk score R was then constructed using the polynomial combination of age, Phe and Gln in the units of micromolar (μM):Formula: see text R correlates with the time to HCC significantly (Hazard ratio HR = 2.368, 95% confidence interval CI 1.760-3.187, P < 0.001). An additional cross-sectional analysis showed that Phe and Gln concentrations both correlates with HCC occurrence in the next 3 years (area under the receiver operating characteristic curve AUC = 0.607 and 0.629, P = 0.033 and 0.010 respectively). In conclusion, phenylalanine and glutamine concentrations in the peripheral blood correlate with subsequent HCC.