Abstract: Objective To investigate the expression of Livin and Smac proteins in esophageal squamous cell carcinoma (ESCC) tissue and their relationship to the progression of ESCC. Methods Expressions of Livin and Smac proteins were respectively detected by immunohistochemistry SP method in 62 cases of ESCC, in 31 cases of paracancerous atypical hyperplasia, and in 62 cases of normal esophageal mucosa. Then the relationships between Livin and Smac protein expressions and clinicopathologic features of ESCC patients were estimated. Results Of the 62 ESCC patients, ther diagnosis of ESCC were confirmed by histopathological detection, 15 cases were grade Ⅰ, 25 cases were grade Ⅱ, 22 cases were grade Ⅲ; 20 cases have lymph node metastasis; and 7 cases were followed with invasion of mucosa, submucosa, or shallow layer, 14 cases have invasion of deep muscle, 41 cases have invasion of fiber membrane. Livin protein were lower expressed in normal esophageal mucosa, but high expressed in paracancerous dysplasia and esophageal cancer tissues, and the difference among the 3 groups was statistically significant (χ2=22.742，P<0.05). Smac protein were overexpressed in paracancerous dysplasia, but less expressed in normal esophageal mucosa and esophageal cancer tissues, and the difference among the 3 groups was statistically significant (χ2=9.688,P<0.05). Livin and Smac protein expressions in ESCC tissues were not affected by the patients' gender and age, however it was significantly correlated with the histological grade, depth of invasion or lymph node metastases (P<0.05). The expression of Livin and Smac proteins was negatively correlated with the progression of ESSC （r=－0.426，P<0.05）. Conclusion Abnormal expression of Livin and Smac occured in ESCC, which suggested that Livin and Smac play important role in the development, invasion and metastasis of ESCC.