This report describes a 46-year-old white man who suffered an acute myocardial infarction after carbon monoxide exposure. The electrocardiogram and serum enzymes showed myocardial infarction. The coronary angiogram performed one week after admission failed to reveal evidence of coronary obstructive lesions. The case presented is of interest because the clinical presentation suggestive of myocardial infarction was absent, the patient was found unconscious and his medical profile was negative for coronary heart disease risk factors. It is assumed that COHb causes myocardial infarction by severe generalized tissue hypoxia and a direct toxic effect on the myocardial mitochondria. Contributing factors that might also decrease myocardial oxygenation are an inadequate myocardial perfusion and an increased thrombotic tendency.