Superior mesenteric artery syndrome was observed in an adolescent patient. He had a 1-day history of nausea, vomiting, and abdominal pain, without chronic or recurrent symptoms. Diagnosis was established by abdominal plain x-ray, contrast enhanced abdominal computed tomography, and endoscopic examination. The patient was hospitalized, monitorized, and decompressed by nasogastric tube without oral feeding. The symptoms of the patient were gradually relieved by conservative treatment and he was discharged after one week. Clinicians should be careful when facing upper gastrointestinal symptoms that are resistant and non-responsive to treatment, and this syndrome should be kept in mind. This case is presented to draw attention to this disease because of its rare incidence.