BACKGROUND: Myocardial involvement in Behcet\'s disease has been reported to be relatively rare. OBJECTIVE: To evaluate myocardial involvement noninvasively in patients with Behcet\'s disease by measuring signal-averaged electrocardiography (SAECG), QT dispersion and heart rate variability (HRV). PATIENTS AND METHODS: The study group comprised 28 eligible patients (16 male, mean age 37+/-13 years) of 33 patients with Behcet\'s disease, and 25 age- and sex-matched control subjects. RESULTS: The echocardiographic left ventricular measurements were within normal limits and similar in both groups except the E/A ratio, which was significantly lower in patients with the disease than in control patients. Minimal pericardial effusion was detected in four patients. Considering the SAECG recordings, values of root mean square voltage in the last 40 ms were 30+/-18 microV and 38+/-18 microV in patients with Behcet\'s disease and in the control group, respectively. The number of cases with a value less than 20 microV was seven (25%) and one (4%) in the same groups, respectively. Both QT dispersion and the corrected QT interval dispersion were significantly increased in patients with Behcet\'s disease compared with the control patients (50.2+/-16.6 versus 20.4+/-18.8, P<0.01). Although all HRV measures appeared to be decreased in the Behcet\'s group, only the standard deviation of all filtered RR intervals in the entire 24 h ECG recordings and the percentage of differences between adjacent filtered RR intervals that are greater than 50 ms for the whole analysis values differed significantly between the groups (P<0.05). No significant difference was observed in frequency domain parameters. In the Holter ECG recording, grade 2 or greater premature ventricular complexes were observed in seven patients from the Behcet\'s group (25%) but in only one subject from the control group (4%) (P<0.05). CONCLUSIONS: Patients with Behcet\'s disease appeared to have significantly increased QT dispersion, a left ventricular diastolic dysfunction pattern in echocardiography, a high incidence of positive late potentials and more complex ventricular arrhythmias, suggesting myocardial involvement and the existence of an arrhythmogenic substrate, whereas the HRV measures do not suggest a clear autonomic abnormality in Behcet\'s disease.