An unusual case of idiopathic giant cell myocarditis (GCM) is described. The patient had a 5-year history of stable and unstable angina, poorly controlled by medical treatment. He underwent a successful coronary artery bypass, but 2 months later died suddenly at home. A coroner's autopsy revealed isolated GCM. This newly described possible association between the surgery and the condition is discussed and the pertinent literature is reviewed. We suggest that the list of causes of GCM in postoperative patients should also include foreign-body reaction. Our findings support the view that myocarditis occasionally masquerades as fatal acute myocardial infarction.