Objective:To determine the expression of Mcm2(a member of MCMs family) in colorectal neoplasm and to assess the relationship between Mcm2 expression and clinicopathological characteristics of colorectal neoplasm.Methods: Immunohistochemical staining was used to detect the expression of Mcm2 in normal colorectal mucosa(n=23),adenoma(n=33),and cancer(n=69) tissues,and the results were quantified by calculating the labelling index(LI).Results: Mcm2 expression in normal colorectal mucosa was confined to the 1/3-1/2 of colonic crypts basal;there was no expression in coloncytes surface.In colorectal adenoma and cancer,Mcm2 expression was seen throughout epithelium,including the coloncytes surface.The median(range) LI of Mcm2 in these 3 tissues were 18%(5%-37%),35%(15%-75%),66%(41%-90%),respectively.The differences between normal mucosa,adenoma and cancer were statistically significant(P