Objective To evaluate the relationship between endoscopic rectal aberrant crypt foci (ACF) and colon neoplasm, including lesions with high risk of aggressive progression (adenoma with diameter ≥ 1cm, villus adenoma, tubular-villus adenoma, adenoma of high grade dysplasia, or cancer). Methods The rectum of 212 patients who underwent colonoscopy was stained by 0. 4% indigo armine, and the patient was classified into different grade according to the number of rectal ACF, namely Grade 0 as no ACF, Grade Ⅰ as 1-4, Grade Ⅱ as 5-9 and Grade Ⅲ as more than 10. The correlation between rectal ACF grade and colon lesions was analyzed. Results Of 212 patients, 72 were classified as Grade 0, 48 as Grade Ⅰ , 41 as Grade Ⅱ, and 51 as Grade Ⅲ. The detection rate of colon neoplasm and lesions with high risk of aggressive progression in patients with rectal ACF were significantly higher than that in patients without rectal ACF (OR at 95% CI was 22. 352 (6. 716 -74. 395) and 7. 982 ( 1. 838-34. 672), respcetively). Conclusion Rectal ACF may predict the detection of colon lesions, including those with high risk of aggressive progression.