Danon disease is a rare X-linked dominant metabolic disorder caused by a primary deficiency in lysosome-associated membrane protein 2. It is characterized by the development of cardiac disease, skeletal myopathy and cognitive disorder. Due to the rarity of Danon disease, physicians may be unfamiliar with the phenotype, confusing it with hypertrophic cardiomyopathy or other causes of left ventricular hypertrophy. The present report demonstrates the clinical value of cardiac magnetic resonance imaging for the diagnostic work-up of Danon disease.