Superior mesenteric artery (SMA) syndrome is an uncommon disease that results from SMA compression of the third portion of the duodenum. Patients with SMA syndrome present with upper gastrointestinal symptoms, such as nausea, vomiting, and abdominal pain. The diagnosis is usually made from an upper barium study or computed tomography. Typically, SMA syndrome is caused by a decreased aortomesenteric angle of 6° to 25°. An underweight body mass index (BMI) is a risk factor for development of SMA syndrome. There are few reports of the role of linear endoscopic ultrasound (EUS) in the diagnosis of SMA syndrome. We report a case of SMA syndrome, with normal BMI, that was diagnosed with the aid of linear EUS. Although SMA syndrome is not typically within the scope of practice of endosonographers, it is useful to get familiar with the findings.