OBJECTIVE Histological features of chronic active ileitis in the small intestine neighbouring a Meckel's diverticulum raise the possibility of concurrent Crohn's disease. Several studies have reported a significant association between Meckel's diverticulum and Crohn's disease, whereas some case reports have proposed that the ileitis is attributable to acid-secreting gastric heterotopia. The aim of this study was to evaluate the incidence, histomorphology and clinical follow-up of Meckel's diverticulum-associated ileitis. RESULTS Medical records and slides from 48 consecutive surgical resections performed for Meckel's diverticulum were reviewed. Nine of 48 adults had significant inflammatory changes in the small intestine neighbouring the diverticulum. Two were transmural ulcers attributable to ingestion of a sharp object. Two patients had established Crohn's disease, both with long segments (>95 mm) of transmural inflammation located >100 mm from the diverticulum. The remaining five patients had inflammatory changes (ulceration, pseudopyloric metaplasia, submucosal fibrosis, and muscularis mucosa hyperplasia) confined to a short segment (<20 mm) of mucosa/submucosa within 50-60 mm of the diverticulum. Two had gastric heterotopia in the diverticulum. None of these five patients used non-steroidal anti-inflammatory drugs (NSAIDs). On follow-up, none had symptoms, imaging or pathology suggestive of Crohn's disease. CONCLUSIONS Ileitis affecting a short segment of mucosa and submucosa in the small intestine near a Meckel's diverticulum is relatively common, and is not necessarily related to Crohn's disease.