Objective To investigate the association between body mass index(BMI),waist circumference(WC),waist hip ratio(WHR) and the risk of colorectal adenoma,which was considered as a precancerous lesion.Methods Subjects aging from 25 to 88 years old who underwent colonoscopy at Tongji Hospital from December 2006 to December 2007 were selected and assigned into the adenoma group( n =250) and the control group(n=289) according to the findings of the colonoscopy.The body height,weight,waist and hip circumference of every subject were measured respectively.The logistic multi-factors regression analysis was applied to analyze the data.Results When obesity was determined by BMI or WC,the risk of adenorrm in pure obesity group and abdominal adiposity group was 2.48(95%CI = 1.19～5.20,P<0.05) and 1.75(95%CI=1.15～2.66,P<0.01 ),respectively.The corresponding value in male was 4.10(95%CI = 1.26～13.31,P<0.05) and 1.70(95%CI = 1.00 -2.88,P<0.05).The risk of advanced and non-advanced adenoma in pure obesity was 2.71(95%CI=1.01～7.29,P<0.05 ) and 2.39(95%CI=1.05～5.47,P<0.05) ; the risk of non-advanced adenonm in abdominal adiposity group was 2.03(95%CI=1.25～3.28,P<0.01),but no significant difference in risk of advanced adenoma was detected.When obesity was determined by WHR,no significant difference was found in any regarding.Conclusion Obesity and abdominal adiposity are associated with the risk of colorectal adenoma,beth advanced and non-advanced,which is more obvious in male.