Despite tremendous efforts to develop curative agents, there are few effective drugs for the treatment of hepatocellular carcinoma (HCC). This is predominantly due to the variations in individual HCC cases. As numerous HCC cases have no mutations in known tumor-associated genes, identification of novel genes involved in the development and progression of human cancers is considered to be an urgent issue. In the present study, surgical specimens of HCC were analyzed for the expression patterns of ubiquitin-conjugating enzyme, cell division cycle 34 (CDC34), which is hypomethylated in its promoter region and exhibits elevated expression levels in mouse skin tumors. The results of the current study clearly indicated that the elevated CDC34 expression level in cancerous regions was significantly associated with favorable clinicopathological features, such as reduced alanine aminotransferase (ALT) levels and histological grades. Similarly, a higher T/N ratio, which is the ratio of CDC34 expression in HCCs to that in non-tumorous tissues, was significantly associated with favorable features, such as a lower indocyanin green retention rate after 15 min (ICG15R), reduced α-fetoprotein and smaller tumor size. These results indicate that the CDC34 expression level in HCC is a marker for predicting the HCC prognosis and that CDC34 acts as a tumor suppressor.