AbstractCytokines play an important role in the pathogenesis of cirrhosis and hepatocellular carcinoma (HCC), most cases of which are related to either hepatitis B virus (HBV) or hepatitis C virus (HCV). Prior studies have examined differences in individual cytokine levels in patients with chronic liver disease, but comprehensive cytokine profiling data across different clinical characteristics are lacking. We examined serum cytokine profiles of 411 patients with HCC (n = 102: 32% HBV, 54% HCV, 14% non-viral) and without HCC (n = 309: 39% HBV, 39% HCV, 22% non-viral). Multiplex analysis (Luminex 200 IS) was used to measure serum levels of 51 common cytokines. Random forest machine learning was used to obtain receiver operator characteristic curves and to determine individual cytokine importance using Z scores of mean fluorescence intensity for individual cytokines. Among HCC and non-HCC patients, cytokine profiles differed between HBV and HCV patients (area under curve (AUC) 0.82 for HCC, 0.90 for non-HCC). Cytokine profiles did not distinguish cirrhotic HBV patients with and without HCC (AUC 0.503) or HCV patients with and without HCC (AUC 0.63). In conclusion, patients with HBV or HCV infection, with or without HCC, have distinctly different cytokine profiles, suggesting potential differences in disease pathogenesis and/or disease characteristics.