INTRODUCTION: Zwint, a centromere-complex component required for the mitotic spindle checkpoint, has been reported to be overexpressed in different human cancers, but it has not been studied in human hepatocellular carcinoma (HCC). MATERIALS AND METHODS: The role of Zwint in hepatocellular carcinoma cell proliferation capacities was evaluated by using cell counting kit-8 (CCK8), flow cytometry, clone formation and tumor formation assay in nude mice. Western blot analysis and qPCR assay were performed to assess Zwint interacting with cell-cycle-related proteins. RESULTS: We report that ZWINT mRNA and protein expression were upregulated in HCC samples and cell lines. An independent set of 106 HCC-tissue pairs and corresponding noncancerous tissues was evaluated for Zwint expression using immunohistochemistry, and elevated Zwint expression in HCC tissues was significantly correlated with clinicopathological features, such as tumor size and number. Kaplan-Meier survival and Cox regression analysis revealed that high expression of Zwint was correlated with poor overall survival and a greater tendency for tumor recurrence. Ectopic expression of Zwint promoted HCC-cell proliferation, and Zwint expression affected the expression of several cell-cycle proteins, including PCNA, cyclin B1, Cdc25C and CDK1. CONCLUSION: Our findings suggest that upregulation of Zwint may contribute to the progression of HCC and may be a prognostic biomarker and potential therapeutic target for treating HCC.