Abstract: Objective: To investigate the correlation between expression of occludin in human hepatocellular carcinoma(HCC) and the genesis and development of HCC.Methods: The expression and cellular distribution of occludin were detected by immunohistochemistry.The cellular structure of HCC was observed by hematoxylin-eosin(HE) staining.Results: Immunohistochemistry indicated that occludin was mainly located in the cell junction area.The positive rate of normal liver tissue was higher than that of tumor tissue(P<0.01).The ++-++ grade intensities of non-tumor liver tissue were stronger than those of the tumor tissue(P<0.005).There was no significant difference between the normal tissue and the cancer with better differentiation(Ⅰ,Ⅱ grade) in 10 cases(P>0.05),while the difference was significant between the normal liver tissue and the corresponding HCC tissue with worse differentiation(Ⅲ,Ⅳ grade) in 33 cases(P<0.05).Conclusions: The expression of occludin in hepatocellular carcinoma decreases significantly in both positive rate and intensity compared with that in normal tissue.The decreased expression of occludin may play an important role in the genesis and development of HCC.