AIM: To evaluate how proximal colon polyps interpreted as hyperplastic polyps in 2001 would be interpreted by expert pathologists in 2007. METHODS: Forty consecutive proximal colon polyps ≥ 5 mm in size, removed in 2001, and originally interpreted as hyperplastic polyps by general pathologists at Indiana University, were reviewed in 2007 by 3 GI pathologists. RESULTS: The gastrointestinal (GI) pathologists interpreted 85%, 43% and 30% of the polyps as sessile serrated polyps (sessile serrated adenomas). The overall Kappa was 0.16. When diagnoses were compared in pairs, Kappa values were 0.38 and 0.25 (fair agreement) and 0.14 (slight agreement). CONCLUSION: Many polyps interpreted as hyperplastic in 2001 were considered sessile serrated lesions by GI pathologists in 2007, but there is substantial inter-observer variation amongst GI pathologists. AIM: To evaluate how proximal colon polyps interpreted as hyperplastic polyps in 2001 would be interpreted by expert pathologists in 2007. METHODS: Forty next proximal colon polyps ≥ 5 mm in size, removed in 2001, and originally interpreted as hyperplastic polyps by general pathologists at Indiana University, were reviewed in 2007 by 3 GI pathologists. RESULTS: The gastrointestinal (GI) pathologists interpreted 85%, 43% and 30% of the polyps as sessile serrated polyps (sessile serrated adenomas). The overall Kappa was 0.16. When diagnoses were compared in pairs, Kappa values ​​were 0.38 and 0.25 (fair agreement) and 0.14 (slight agreement). CONCLUSION: Many polyps interpreted as hyperplastic in 2001 were considered sessile serrated lesions by GI pathologists in 2007, but there is substantial inter-observer variation amongst GI pathologists.