Abstract: Objective : To investigate the expression of p27 ^Kip1 phosphorylated at the threonine 187 (Thr187) and ser-ine 10 (Ser10) residues (P-p27Thr187, P-p27Ser10) and its significance in hepatocellular carcinoma (HCC). Methods : We used immunohistochemistry to detect the expression of P-p27Thr187, P-p27Ser10 and total p27 in 10 samples of liver tissue adjacent to hepatic hemangioma and 76 samples of HCC tissue with corre-sponding adjacent non-tumor tissue.Fresh specimens from 6 cases of HCC and the adjacent liver tissue were also collected for Western blot analysis.The expression of phosphorylated p27 was analyzed and com-pared with that of proliferative cell nuclear antigen (PCNA). Results : Western blot analysis showed that phos-phorylated p27 protein expression in HCC tissue was higher than that in adjacent non-tumor liver tissues.Im-munohistochemistry showed that phosphorylated p27 and PCNA expression were higher in HCC tissues ( P < 0.001).There was a positive correlation between phosphorylated p27 and PCNA ( P <0.001).An inverse corre-lation was found between phosphorylated p27 and total p27 in HCC ( P <0.001).The expression of phosphory-lated p27 was correlated with histological differentiation, serum alpha-fetal protein levels and necrosis ( P < 0.05).In addition, the expression of P-p27Ser10 was associated with metastasis ( P <0.05). Conclusion : The expression of phosphorylated p27 was upregulated significantly in HCC compared with non-tumor tissues.Overexpression of phosphorylated p27 may play an important role in the oncogenesis and development of HCC.