Myotonic dystrophy is an autosomal inherited disorder of both striated and smooth muscle, and is considered to be a rare cause of gastrointestinal dilatation and abnormal peristalsis. We report on a patient with myotonic dystrophy complicated by gastric volvulus. A 57-year-old female with myotonic dystrophy suddenly developed abdominal pain, nausea and vomiting. X-ray examinations revealed gastric dilatation and pyloroantral obstruction, consistent with acute gastric volvulus. The patient underwent successful emergency gastrectomy. Gastric volvulus is often an unrecognized surgical emergency, but its clinical and radiographic features are so characteristic that accurate diagnosis is possible if the condition is kept in mind. Thus, the clinician should consider the possibility of gastric volvulus when evaluating gastrointestinal complaints in patients with myotonic dystrophy.