Objective: To investigate expression and significance of PTEN gene in primary hepatocellular carcinoma (HCC). Methods: Immunohistochemical peroxidase-conjugated streptavidin (SP) method was used to detect expression of PTEN gene in 120 cases of primary HCC and its adjacent tissue 10 cases of normal liver tissue. The relationship between expression of tumor suppressor gene of PTEN and the percentage of lymph node metastasis of HCC was analyzed. Results: It was shown that PTEN gene was expressed in all 10 cases of normal liver tissues and paracancerous liver tissues. The staining was localized mainly in cytoplasm. Expression of PTEN in 120 cases of HCC were as follows: 12.5% were negative, 17.5% were weak positive, and 70% were strong positive. At time of diagnosis, 33/120 (27.5%) presented lymph node metastasis. Lymph node metastases were present in 80% (12 out of 15) PTEN negative HCC, 57.14% (12 out of 21) PTEN weak positive HCC and only 10.71% (9 out of 84) PTEN intense positive HCC, (P<0.05). Therefore, PTEN tumor suppresor gene malfunction seems to be involed in mtastasing capacity of HCC. Conclusion: This study suggests that PTEN gene was deleted or weakly expressed in primary hepatocellar carcinoma, which is probably related to its tumorigenesis.