Nonsteroidal anti-inflammatory drugs (NSAIDs) have both beneficial and deleterious effects on the colon. Long-term use is associated with a substantial decrease in colorectal cancer incidence and regression of adenomatous polyps. In contrast, significant adverse effects are also interesting, but rare, and include mucosal inflammation and ulceration, exacerbation of inflammatory bowel disease, diverticular bleeding, and diaphragm-like stricturing of the proximal colon. Discontinuation of the offending drug results in symptom resolution in the majority of cases, but some require endoscopic balloon dilation or surgical resection of strictures.