Myocardiopathy (MCP) is diagnosed by exclusion in patients with congestive heart failure in the absence of lesions of the coronary vessels or cardiac valves. Endo-myocardial biopsies and several cases of clinical improvement under immunosuppressive therapy suggest that it may be due due to an immune mechanism. Gallium-67 is taken up by the myocardium and may be regarded as a scintigraphic marker of myocardial inflammation. It may therefore be used to determine which patients would benefit from immunosuppressants. Our study involved 47 patients (mean age 40.1 +/- 10.2 years) with MCP evidenced by angiography and coronary arteriography. Isotopic ejection fraction (EF) and Ga-67 uptake by the myocardium were evaluated in all cases. A significant Ga-67 uptake was observed in 22 patients, 20 of whom could be divided into two groups: group I received an immunosuppressive treatment (azathioprine plus prednisone); group II did not receive such treatment. A new radionuclide cardiac examination was carried out 5 months after the beginning of treatment. No significant Ga-67 uptake could be detected in either group. Significant improvement of EF was observed in 6 patients of group I and in 2 patients of group II. Four patients had died: 1 in group I and 3 in group II. Thus, a decrease in Ga-67 uptake was noted in all patients 5 months after the initial examination, irrespective of the treatment received, which suggests that this decrease belongs to the natural history of the disease. The effect of immunosuppressive therapy on MCP, therefore, ought to be re-evaluated.