Marfan syndrome is a heritable disorder of connective tissue in which the most prominent abnormalities occur in the ocular, cardiovascular and skeletal systems. Although cardiovascular complications are infrequent in patients under 20 years of age, whenever they do occur, they are the major cause of death. Here we report three cases in a Chinese family with clinical evidence of myocarditis associated with Marfan syndrome. The 99Tcm-hexamethylpropyleneamine oxime (HMPAO)-labelled white blood cell and 201Tl single photon emission computed tomographic heart scans show indications of an inflammatory process involving the myocardium. After comparison with the pathology results, the accuracy of these studies is seen to be 100%. We thus introduce these simple methods to evaluate myocardial viability in patients with Marfan syndrome.