We detected the cytotoxicity and synergistic effect of the combination of CD55‐TMn and Dox in HCC cell line Hep G2, Hep 3B and PLC/PRF/5 treated with CD55‐TMn at various MOIs (1, 2 and 4) and Dox (0.2 μg/ml). This evidence concerns the gene CD55 and hepatocellular carcinoma.