A prospective clinical and echocardiographic study of 47 patients with systemic lupus erythematosus (SLE) and 46 age- and sex-matched controls showed an increased prevalence of echocardiographic abnormalities in the SLE group. Pericardial abnormalities were identified in ten patients with SLE and in no controls. Excluding mitral valve prolapse, valvular abnormalities were identified in ten patients with SLE (21%) and in three controls (7%). In the patients with SLE, abnormalities included mitral valve leaflet thickening in six, aortic valve thickening in five, and mitral annular calcification in two. The presence of valvular abnormalities correlated with duration but not with severity of SLE. The finding of systolic murmurs in 17 of 47 patients with SLE did not correlate with echocardiographic evidence of valvular disease. In six patients with SLE, valvular abnormalities detected by two-dimensional echocardiography were not seen on M-mode echocardiogram.