Fourteen patients with polymyositis-dermatomyositis (PM-DM) underwent prospective cardiac assessment with non-invasive techniques. One patient had electrocardiographic evidence of Long-Ganong-Levine syndrome with multiple supraventricular premature beats. Echocardiographically one patient had late systolic prolapse of the posterior mitral leaflet and another had paradoxical movements of the interventricular septum. The study suggests that cardiac involvement is infrequent in PM-DM.