A pair of 37-year-old identical twins with diabetes mellitus are described. One of the brothers was admitted for heart failure without pain, and autonomic neuropathy was found. The clinical diagnosis was inferior myocardial infarction with anteroseptal healed myocardial infarction. Cardiac catheterization revealed triple coronary vessel involvement. The diagnosis was confirmed at autopsy after sudden death. The other brother was also examined by cardiac catheterization, which revealed total right coronary occlusion and hypokinesis of the wall. There had been no previous pain nor upper body discomfort until that time in either twin. Thus, genetic factors should possibly be considered in the genesis of asymptomatic or silent myocardial infarction.