Thirteen patients with non-specific aortoarteritis and endomyocardial biopsy evidence of myocarditis were followed-up on immunosuppressive therapy comprising of prednisolone and cyclophosphamide in addition to conventional treatment for hypertension and/or congestive heart failure. Serial determinations of erythrocyte sedimentation rate, chest roentgenogram, radionuclide ventriculogram and hemodynamic study including endomyocardial biopsy were carried out at 12, 24 and 52 weeks of therapy. Arterial lesions were also assessed by digital subtraction angiography at 0 and 52 weeks of immunosuppressive therapy. At the end of a year of treatment all patients with congestive heart failure (10/13) showed symptomatic improvement by at least one New York Heart Association (NYHA) class. There was a significant fall in erythrocyte sedimentation rate (48 +/- 12 mm/1st h to 31 +/- 12 mm/1st h, P < 0.05), pulmonary artery pressure (32 +/- 14 mmHg to 20 +/- 9 mmHg, P < 0.05), left ventricular filling pressure (20 +/- 11 mmHg to 11 +/- 7 mmHg, P < 0.05) and increase in left ventricle ejection fraction (39 +/- 16% to 51 +/- 14%, P < 0.05) associated with resolution of morphological changes on endomyocardial biopsy. Arterial lesions remained static with neither progression nor appearance of new lesions. No significant complications of therapy were noticed in any patient. Our uncontrolled observations suggest that immunosuppressive therapy is safe and results in clinical, hemodynamic and myocardial morphological improvement in a subset of patients with non-specific aortoarteritis and associated myocarditis.