Echocardiography was used to evaluate the heart in 19 patients with one of various systemic diseases known to be associated with infiltrative cardiomyopathy. Four patients had systemic amyloidosis, 10 had idiopathic hypereosinophilia and 5 had iron overload caused by multiple blood transfusions. Although 10 patients (53 percent) had no clinical evidence of cardiac disease, all 19 had echocardiographic abnormalities; the left ventricle was symmetrically thickened (more than 11 mm) and left ventricular mass was increased (more than 275 g) in all; the left ventricular transverse dimension was modestly increased (more than 52 mm) in 5 patients (26 percent) and the velocity of mitral valve closure in early diastole was reduced (less that 60 mm/sec) in 5 patients. Systolic function, as evidenced by ejection fraction, was well maintained (greater than 60 percent) in 18 of 19 patients. Thus, it appears that echocardiographic abnormalities can be detected in many patients with a systemic disease associated with infiltrative cardiomyopathy even before clinically evident heart disease develops.