Abstract: Abstract　Objective: To study the expression of mitochondrial hinge protein ( MHP ) in hepatocellular carcinoma ( HCC ), to explore its clinicopathologic significance, and to study the relationship between MHP expression and the malignant behavior of HCC. Methods: The SP immunohistochemical method was used to determine MHP expression in paraffin-embedded sections from 80 HCC cases, 80 juxtacancerous specimens, and 50 normal liver tissue samples. Results: The MHP-positive rates and scores were significantly higher in the HCC cases than in the juxtacancerous specimens and normal liver tissues ( P < 0.05 ). No significant differences were observed between the juxtacancerous specimens and normal paraneoplastic liver tissues ( P < 0.05 ). MHP expression was significantly correlated with tumor size and tumor thrombli in the portal vein of HCC ( P < 0.05 ), but not with sex, age, liver cirrhosis, or the alphafetoprotein ( P > 0.05 ). Conclusion: MHP expression significantly correlates with the malignant behavior of HCC. This protein may be an important biological marker for the carcinogenesis, tumor progression, biological behavior, and prognosis of HCC.