Herein, we investigated the possible roles of 13 core circadian clock genes in HCC, including ARNTL, CLOCK, CRY1, CRY2, DBP, NR1D1, NR1D2, NPAS2, PER1, PER2, PER3, RORA, and TIMELESS. This evidence concerns the gene NR1D1 and hepatocellular carcinoma.