Hypertrophic cardiomyopathy(HCM) is defined as a thickened wall of heart muscles and non-dilated left ventricle, but is not accompanied underlying cardiac or systemic diseases that induce ventricular hypertrophy. HCM is responsible to exercise limitation for all ages and also is known as the most common cause of heart-related sudden death during childhood and adolescents. Epidemiological studies showed that prevalence in young adults is 0.2% and HCM is caused by a mutations in genes that code the proteins of cardiac muscles. HCM with Wolff-Parkinson-White Syndrome is extremely rare and associated with a high risk of tachyarrhythmia and sudden death. We report an infantile HCM with WPW syndrome who died suddenly.