Oxyntic gastric heterotopia (GH) in the colon is not common. Its presence in a colon tubular adenoma is even rare. A 73-year-old woman with a history of resected colon carcinoma underwent periodical colonoscopies for the removal of tubular adenomas for 12 years. In the last colonoscopy, a sessile, non-ulcerated polyp, centrally depressed, with a smooth surface, measuring 20 mm, located at 50 cm from the anal verge was excised. A histological study identified a tubular adenoma with focal low-grade dysplasia and ectopic gastric oxyntic epithelium. The GH, composed of parietal and chief cells, and was found incidentally. Oxyntic GH in a tubular adenoma is extraordinarily rare. To the best of our knowledge, there is only one previously published case. The main possible difficulties and∕or errors in the diagnosis include a tissue floater or a cross-contaminant. Precise diagnosis of oxyntic GH is basic for appropriate management. Diagnosis relies on histopathological examination. The immunohistochemical study for mucin 6 (MUC6) can confirm the nature of the epithelium. Oxyntic GH has the potential to produce serious complications including tumor development. However, GH is considered a benign disease and adenocarcinoma rarely occurs in the heterotopic mucosa. The optimal treatment of oxyntic GH associated with a tubular adenoma is endoscopic complete polypectomy.