A case of a heterotopic gastric cyst of the oral cavity is described and a review of the literature, with emphasis on the possible etiological theories of this rare lesion, is presented. This developmental lesion is found more commonly in males. It most likely arises from misplaced embryonal tissue. Surgical treatment is the preferred choice of treatment, and CO2 laser is a safe alternative surgical approach for the removal of this lesion. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.