The incidence and nature of cardiac involvement in Behçet's disease are not yet clearly documented. We first used transesophageal echocardiography in combination with resting and signal averaged electrocardiography to define cardiac involvement in Behçet's patients. Transthoracic and multiplane transesophageal echocardiography, and resting and signal averaged electrocardiography were performed in 35 Behçet's disease patients (9 women and 26 men, mean age: 38 +/- 12 years) and 30 normal subjects. Higher incidences of interatrial septum aneurysm (31% to 6%), mitral valve prolapse (25% to 3%), mitral regurgitation (40% to 6%) and aneurysmal dilatations of sinus valsalva and ascendan aorta were observed in the Behçet's disease patients than in the normal subjects. Mean QT dispersion and mean corrected QT dispersion values were significantly greater in the patients with Behçet's disease. Patients with interatrial septum aneurysm (and/or PFO), valvular dysfunction or proximal aorta dilatation had greater QT dispersion values than thase without these pathologies in the Behçet's group (63 +/- 11 vs 44 +/- 19 ms, 58 +/- 23 vs 41 +/- 24 and 60 +/- 27 vs 42 +/- 23 ms respectively, P<0.05). Positive signal averaged electrocardiography parameters were detected in 18 (51%) Behçet's disease patients compared with one (3%) in controls (P<0.001). Dilatation of the proximal aorta, interatrial septal aneurysm, mitral valve prolapse, and mitral regurgitation are the common findings of cardiac involvement in Behçet's disease. Increased dispersion of ventricular repolarisation and positive late potentials are also detected. QT dispersion is significantly higher in patients with these cardiac abnormalities. These findings suggest that cardiac involvement in this disorder is a diffuse process which involves both cardiac structure and vascular elements.