Hypertrophic cardiomyopathy (HCM) may have sudden death as its first presentation. This case presentation describes a 25-year-old man with post-mortem finding of previously unknown left ventricular hypertrophy. Genetic analysis revealed a mutation in the myosin-binding protein C (MYBPC3). Autopsy combined with molecular genetic screening for mutations may give the relatives certainty of cause of death and the opportunity for genetic screening for diagnosis and treatment as well as prevention of sudden cardiac death.