Herein, we systematically characterized the expression pattern of core circadian clock genes, including ARNTL, CLOCK, CRY1, CRY2, DBP, NPAS2, NR1D1, NR1D2, PER1, PER2, PER3, RORA, and TIMELESS, and their clinical significances in HCC. This evidence concerns the gene PER3 and hepatocellular carcinoma.