Superior mesenteric artery (SMA) syndrome is an unusual form of duodenal obstruction. Complications of SMA syndrome may sometimes develop and are usually associated with marked gastric dilatation, although most complications can be corrected by supportive treatment. In this article, we report a case of severe SMA syndrome with hypovolemic shock in a 24-year-old man. Multidetector-row computed tomography with reconstructed images was performed to establish the diagnosis. Spontaneous gastrointestinal bleeding is an extremely uncommon complication of SMA syndrome, and emergent surgical intervention was unavoidable in our patient. To our knowledge, no other such case has been reported in the English-language literature.