Objective To investigate the relationship between β glucuronidase and tumor differentiation and invasion in human colorectal carcinoma.Methods The expression of β glucuronidase in human colorectal carcinoma tissue was determined by streptavidin peroxidase immunohistochemical method. Four human colorectal carcinoma cell lines were analysed for β glucuronidase in the medium by spectrophotometry method.Results Compared with well differentiated colorectal carcinomas, β glucuronidase expression was higher in poorly differentiated tumors. An association was found between β glucuronidase overexpression in colorectal carcinoma and more advanced tumor Dukes’ stage ( P <0.05). With increasing maximum depth of invasion, tumors more frequently show higher β glucuronidase expression (P<0.05). The analysis of colorectal carcinoma cell lines for β glucuronidase showed that low levels of β glucuronidase (activity range, 1.29 to 1.96?μg/10 6 cells per hour) were associated with the well differentiated cell lines which have low invasiveness (CX1, CCL187), and this was in contrast to the elevated level of the enzyme (2.46 to 2.73?μg/10 6 cells per hour) present in the medium derived from the poorly differentiated cells with high invasiveness (CCLl227,CCL228) (P< 0.05). Conclusions Poorly differentiated human colorectal carcinoma cells could synthesize more β glucuronidase, enhance local invasion. Immunohistochemical staining for β glucuronidase might be helpful to diagnosing the differentiation degree and invasiveness of human colorectal carcinomas, and the secreted β glucuronidase might provide a useful measurement of the differentiation degree and invasiveness of cultured human colorectal carcinoma cells. Objective To investigate the relationship between β glucuronidase and tumor differentiation and invasion in human colorectal carcinoma.Methods The expression of β glucuronidase in human colorectal carcinoma tissue was determined by streptavidin peroxidase immunohistochemical method. Four human colorectal carcinoma cell lines were analysed for β glucuronidase in the Medium by spectrophotometry method.Results Compared with well differentiated colorectal carcinomas, β glucuronidase expression was higher in poorly differentiated tumors. An association was found between β glucuronidase overexpression in colorectal carcinoma and more advanced advanced tumor Dukes’ stage ( P <0.05). With increasing maximum The analysis of colorectal carcinoma cell lines for β glucuronidase showed that low levels of β glucuronidase (activity range, 1.29 to 1.96 μg/10 6 cells per hour ) we Re associated with the well differentiated cell lines which have low invasiveness (CX1, CCL187), and this was in contrast to the elevated level of the enzyme (2.46 to 2.73?μg/10 6 cells per hour) present in the medium derived from the Poorly differentiated cells with high invasiveness (CCLl227,CCL228) (P<0.05). Conclusions Poorly differentiated human colorectal carcinoma cells could synthesize more β glucuronidase, enhance local invasion. Immunohistochemical staining for β glucuronidase might be helpful to diagnosing the differentiation degree and invasiveness of Human colorectal carcinomas, and the secreted β glucuronidase might provide a useful measurement of the differentiation degree and invasiveness of cultured human colorectal carcinoma cells.