Objective:To investigate the relation between the expression of proliferating cell nuclear antigen (PCNA) and prognosis in lung squamous cell.Methods:The expression of PCNA on 51 cases carcinoma tissues were detected by immunohistochemical SP technique. Thet test and F test was used to analyze the difference of expression of PCNA in different pathological grades and clinic stages.Spearman Grade-relation test was used to analyze the relation between PCNA expression and pathological grades.The difference of survival time was compared by Kaplan-Meier curve and Long-rank test in different PCNA expression.Rusults:The position of PCNA expression almostl located in the nuclear,some in cytoplasm.There was difference of PCNA expression in different clinical stages and pathological grades.( P