Abstract: Objective 　To detect the hypermethylation status of the 5'Cp G island locating in the promoter region of p16/ IN K4 gene and it s expression in esophageal squamous cell carcinoma ( ESCC), and to ana2 lyze the relationship between the aberrant methylaion of p16/ IN K4 gene and clinical manifestation. Meth2 ods 　The hypermethylation of the p16/ IN K4 promoter region was detected by methylation specific poly2 merase chain reaction (MSP) in all esophageal cancer tissues, adjacent tissues and each corresponding edge of dissection. With Envision immunohistochemist ry, both esophageal carcinoma tissue and their adjacent mucosa tissue were stained by using the multiclonal antibody against the human P16 protein respectively. Results 　In 75 cases of ESCC, hypermethylation of the p16/ IN K4 promoter region was detected in 5 ca2 ses of dissected edge tissues 6. 67 %(5/ 75), 10 cases of adjacent normal esophageal mucosa 13. 3 %(10/75), 31 cases of ESCC tissue 41. 3 %(31/ 75), respectively. The positive rate of p16 gene expression was 29. 3 %(22/ 75) in ESCC tissues, 56. 7 %(17/ 30) in adjacent mucosa tissues. p16 gene expression was de2 tected in 5 of 31 cases of (16. 1 %) p16 methylation positive ESCC and 17 of 44 cases of (38. 6 % ) p16 methylation negative ESCC. There is a notable difference of hypermethylated rate between lat ter cancer2 ous lesion group and both former normal group s ( P < 0. 01) . There are obvious negative correlation be2 tween p16 gene methylation and p16 gene expression ( P < 0. 01) . No correlation was found between exist2 ence of 5'Cp Gisland of p16 gene hypermethylation in ESCC tissues and histological grade, the position of tumor, but correlated closely with clinical stages and lymphoid metastasis. Conclusion 　The result sup2 port s that the p16/ IN K4 gene promoter hypermethylation might be involved in the pathogenesis of squa2 mous cell carcinoma of the esophagus, and which is closely correlated with the TNM stage and lymphnode metastasis in ESCC.