Objective To observe the expression changes of BAIAP2L2 protein in colorectal cancer(CRC)tissues,and the relationship between its expression and clinicopathological data was discussed.Methods Thirty-one patients with CRC and 33 patients with colorectal polyps were selected.The tumor tissues removed during the operation were recorded as CRC group and CP group,and the normal adjacent mucosal tissues(the normal tissue>5cm away from the cancer tissue)of colorectal cancer patients were recorded as the Control group.Immunohistochemical staining was used to detect BAIAP2L2 protein in the tissues of each group,and semi-quantitative scoring was used to observe the protein expression,including the positive expression rate,area of positive expression and the degree of positivity,and to analyze the relationship between the expression of BAIAP2L2 protein and the clinically relevant parameters of CRC patients.Results BAIAP2L2 protein showed no staining or lighter staining color and small positive area in paracarcinoma tissues as well as polyp tissues,whereas in colorectal cancer tissues the staining was darker,and most of them showed yellow or brownish-yellow granule deposition,suggesting that its expression was higher in CRC tissues.The positive expression rates of BAIAP2L2 proteins in the CRC group,CP group and Control group were 96.8%(30/31),24.2%(8/33)and 3.2%(1/31),respectively,and there was a significant difference in the positive expression rates among the three groups(P<0.001).The positive intensity of BAIAP2L2 protein was differently expressed between CRC group and CP group,CRC group and Control group(all P<0.001),but there was no statistical difference between CP group and Control group(P>0.05).Conclusion The expression of BAIAP2L2 protein in CRC tissues is highly expressed,and the positive intensity is significantly different from that of colorectal polyp tissues and adjacent tissues.