Aims and background: The aim of the present study was to analyze the expression of matrix metalloproteinase-9 (MMP9) in endometrial cancer and its correlation with clinicopathologic features in Chinese patients, including the survival of patients with endometrial cancer.Methods: Using immunohistochemistry analysis, we analyzed MMP9 protein expression in clinicopathologically characterized 128 endometrial cancer (EC) cases with age ranging from 30 to 85 years (median=51.6 years) and 30 endometrial atypical hyperplasia (EAH) and 30 normal endometrium (NE). Cases with greater than or equal to 6 and less than 6 with the score value of cytoplasmic MMP9 immunostaining were regarded as high expression and low expression, respectively. The relationship between the expression levels of MMP9 and clinical features was analyzed in EC cases.Results: Immunohistochemical analysis revealed that the protein expression of MMP9 detected in EC tissues was higher than that in the EAH tissues and NE tissues (P=0.006). In addition, high levels of MMP9 protein were positively correlated with the status of lymph node metastasis (P=0.044) and the histopathological grade (P<0.05) of EC patients. Patients with higher MMP9 expression did not correlate with EC patients' clinical outcome in China. Multivariate analysis suggested that status of lymph node metastasis and depth of myometrial invasion, but not MMP9 expression level, were significantly correlated with patients' survival.Conclusion: MMP9 is highly expressed in ECs and correlates with the progression of ECs, but not be helpful in predicting the prognosis of EC patients.