Superior mesenteric artery syndrome (SMAS), which is also known as the cast syndrome, Wilkie's syndrome, or chronic duodenal ileus, is a specific type of duodenal obstruction characterized by the obstruction of the inferior part of the duodenum due to its compression between the superior mesenteric artery (SMA) and the aorta. This problem is usually resulting from loss of the mesenteric fat pad. The present report describes a case of SMAS who was an 18-year-old woman presenting with weight loss and postprandial pain. The patient was initially diagnosed with Helicobacter pylori infection and underwent antibiotic therapy. However, the related symptoms did not resolve. Finally, she was ordered a CT scan, which led to the diagnosis of SMAS.