NET-1 is a member of the NET-x family. To explore the potential role of NET-1 in hepatocellular carcinoma (HCC), the expression of NET-1 and the relationship with HCC were examined for the first time. We found that NET-1 was frequently expressed in HCC and the peritumor tissue. The relative amounts of NET-1 mRNA in HCC and peritumor tissue were 0.645 +/- 0.37 and 0.466 +/- 0.30, respectively, indicating a higher expression level in HCC than in the peritumor (P < .05). NET-1 protein is usually located on the cell membrane and in the cytoplasm of HCC cells. NET-1 immunoreactivity was found in 126 out of 130 samples of HCC tissue (96.92%). An association of NET-1 expression with cytological variants, histopathological grading, and clinical stages of HCC was also found (P < .05). Detection of NET-1 gene expression in liver biopsy may provide useful information about the biological behavior of HCC.