We performed two-dimensional and Doppler echocardiography in 52 patients with systemic lupus erythematosus and in 34 healthy controls. In 25 patients (48.1%) echocardiographic disturbances were found (25/52 vs 2/34, p<0.001). Valvular abnormalities were detected in 18 patients (34.6%) but in only two controls (18/52 vs 2/34, p<0.01). The mitral valve was involved in 12 patients (23.1%). The most frequent finding was mild (13.5%) and moderate (9.6%) regurgitation or valvular thickening (9.6%). The aortic valve was involved in six and the tricuspid valve in three patients (11.5% and 5.8%, respectively). Only one patient had echocardiographic non-infective verrucous vegetation affecting the tricuspid valve. We did not observe significant hemodynamic valve disease. Endocardial findings were related to disease duration (p<0.05) but not to disease activity. Twenty-eight SLE patients (53.8%) had increased anticardiolipin antibodies (aCL). Patients with aCL (particularly those with IgG class) were characterized by a high incidence of echocardiographic abnormalities (p<0.001), mainly valvular (mitral or aortic) regurgitation (p<0.05). We found a relationship between anticardiolipin antibodies and disease activity (p<0.05). In conclusion, we postulate a prominent role for anticardiolipin antibodies in the pathogenesis of heart valve disease in patients with SLE.