Heterotopic pancreas is a rare disease. We evaluated 17 patients treated surgically at our hospital. Epigastric pain (77%), abdominal fullness (30%), and tarry stools (24%) were the three most frequent symptoms and signs. The lesions were diagnosed as gastroduodenal tumors by gastroduodenoscopy (67%) or upper gastrointestinal series (71%). Among these, only one gastric submucosal tumor was considered to be heterotopic pancreas preoperatively. Three patients were found to have gastric tumor by abdominal ultrasound. Computed tomography, small-intestinal series, barium enema, endoscopic retrograde cholangiopancreatography, angiography, and cholescintigraphy did not help in disclosing lesion. In about half of the patients, the lesions were located at the stomach. Tumor size varied from 1 to 3 cm. Surgical excision relieved symptoms. These findings indicated heterotopic pancreas is still a difficult disease for diagnosis, regardless of the improvements of diagnostic tools and techniques.