To assess the prevalence and the extent of cardiac involvement in patients with Behçet's disease and to investigate the possible causes that may predispose to this involvement, 30 patients affected by Behçet's disease and 30 normal control subjects were submitted to M-mode, two-dimensional, and Doppler echocardiographic evaluation. Moreover, antinuclear and anticardiolipin autoantibodies were determined in the sera of both patients and control subjects. Finally, HLA-B51 positivity was assessed in the patients and in a historical control group. Mitral valve prolapse was observed in 50% and proximal aorta dilatation in 30% of the patients. There was a significant difference in the rate of these abnormalities in comparison with the control group. Left ventricular function parameters were similar between the two groups. The positivity rate of antinuclear and anticardiolipin autoantibodies was very low (7%), without differences between the groups. HLA-B51 was detected in 82.7% of the patients versus 21.7% in the control group (p < 0.00001). In conclusion, this study demonstrates a high rate of cardiac abnormalities in patients with Behçet's disease.