To study causes of gastric outlet obstruction (GOO) in Saudi patients in a tertiary hospital. During one year (between March 2005 and April 2006), twelve patients were referred to the gastroenterology department as possible GOO.All patients had gastroscopy, barium meal and CT scan of abdomen. All patients presented with history of repeated vomiting usually after food. Two of these patients were known to have chronic duodenal ulceration. Gastroscopy in all patients showed food and fluid residue (in spite of fasting more than 12 hours), different lesions were found and biopsied. In patients who had pyloric obstruction, endoscopic dilatation for pyloric canal was done.Four patients had neoplastic disorders (two with adenocarcinomas and one with neuroendocrine tumor and one had lymphoma) and they were referred for surgery. Three patients had chronic duo denal ulceration and two of them were managed by endoscopic pyloric dilatation and medical treatment. One patient had cytomegalovirus (CMV) gastritis together with vitamin B12 deficiency and he improved on medical treatment. One patient had eosinophilic gastroenteritis which improved with medical treatment. One patient had adult congenital pyloric stenosis and serial endoscopic dilatation failed and was referred for surgery. One patient had superior mesenteric artery syndrome and she improved with medical treatment and advises about food and postures and she did not require surgical intervention. Lastly, one patient had GOO secondary to pancreatic tumor and was managed surgically.There are various causes of GOO as shown in our patients, some of which are rare and interesting such as CMV gastritis, adult congenital pyloric stenosis, eosinophilic gastritis and superior mesenteric artery syndrome. Those patients with rare causes will be included in discussion.