201Tl myocardial SPECT was performed to evaluate cardiomyopathy in Duchenne type of progressive muscular dystrophy (DMD). Follow up SPECT images of the same patients were also obtained about 1 year after the first scan. Cases subjected to study were 10 DMD. At the first study the hypoperfusion area of the left ventricular muscle was observed in 6 cases (60%) out of 10. At the second study the hypoperfusion areas became wider and lower in 4 out of 6 cases (66.7%). The new hypoperfusion area which was not demonstrated at the first study was observed at the second study in one case of these cases. These results suggested that the positive rate of cardiomyopathy in DMD by 201Tl myocardial SPECT was high, and 201Tl myocardial SPECT is a useful examination to detect the change of myocardial damage in DMD.