We report on a case of heterotopic gastric mucosa in the body of the gallbladder. A 39-year-old man, who was asymptomatic, visited our hospital because of a polypoid lesion in the gallbladder, discovered during a routine health screening. Ultrasonography (US) revealed a broad-based polypoid lesion 1.7 cm in diameter in the body of the gallbladder, which was free of gallstones. The gallbladder mass was faintly enhanced by helical computed tomography. Laparoscopic cholecystectomy was performed because of the possibility of malignancy. The specimen revealed a 1.7 x 1.3 cm polypoid lesion with deep delle in the body, with no gallstones in the gallbladder. Intraoperative frozen examination yielded a diagnosis of hyperplastic polyp of the gallbladder. Histologically, the polypoid lesion consisted of gastric fundic glands located in the whole wall of the gallbladder. The surrounding mucosa consisted of almost normal epithelium without any metaplastic changes. Postoperative technetium 99m-pertechnetate scintigraphy demonstrated no evidence of gastric heterotopia elsewhere in the body. We also review 18 other reports of heterotopic gastric mucosa in the gallbladder in the Japanese medical literature.