Echocardiographic evaluation of 42 patients with sarcoidosis disclosed 13 patients (group A) with abnormalities compatible with sarcoid heart involvement such as thickening or thinning of the septum (eight patients), pericardial effusion (four patients), and increased end-diastolic dimension of the left ventricle with decreased systolic function (three patients). The remaining 29 patients (group B) were diagnosed as having normal echocardiograms. The clinical data revealed no statistically significant difference between the groups regarding age, sex, chest x-ray stage, activity, and previous heart disease. Group A patients had older clinical onset of the disease (52 vs 83 months; p less than 0.05) and higher incidence of ECG abnormalities than group B patients. There were no statistically significant differences between the groups regarding two-dimensional echocardiographic internal dimensions of both ventricular chambers. The radionuclear right ventricular ejection fraction was low in both groups and the left ventricular ejection fraction was depressed in group A patients (p less than 0.01). As observed in pathologic studies, the septum is a target structure which can be characterized echocardiographically. Screening suspected sarcoid heart disease involvement is important to characterize patients with a relatively high risk of clinical cardiac abnormalities such as complete atrioventricular block, ventricular arrhythmias, congestive heart failure, and sudden death.