A 86-year-old woman hospitalized for analysis of persistent abdominal discomfort died, apparently of myocardial infarction, shortly after admission. Autopsy revealed extensive myocarditis caused by infection with Clostridium septicum. As a portal of entry a carcinoma of the colon was found. The association of colon carcinoma and bacteraemia with C. septicum is well established while colon carcinoma can lead to cardiac hypoxia through blood loss and anaemia. However, myocarditis caused by this organism is extremely rare.