The prevalence of cancer in small and diminutive polyps is relevant to "resect and discard" and CT colonography reporting recommendations.We evaluated a prospectively collected colonoscopy polyp database to identify polyps < 10 mm and those with cancer or advanced histology (high-grade dysplasia or villous elements)Of 32,790 colonoscopies, 15,558 colonoscopies detected 42,630 polyps < 10 mm in size. A total of 4,790 lesions were excluded as they were not conventional adenomas or serrated class lesions.There were 23,524 conventional adenomas < 10 mm of which 22,952 were tubular adenomas.There were 14,316 serrated class lesions of which 13,589 were hyperplastic polyps and the remainder were sessile serrated polyps. Of all conventional adenomas, 96 had high-grade dysplasia including 0.3% of adenomas ≤ 5 mm in size and 0.8% of adenomas 6-9 mm in size. Of all conventional adenomas, 2.1% of those ≤ 5 mm in size and 5.6% of those 6-9 mm in size were advanced. Among 36,107 polyps ≤ 5 mm in size and 6,523 polyps 6-9 mm in size, there were no cancers.These results support the safety of resect and discard as well as current CT colonography reporting recommendations for small and diminutive polyps.