Behçet's disease is often a progressive disorder. In some cases, there is a possibility of subclinical involvement without neurologic signs and symptoms. The autonomic nervous system is affected in Behçt's disease. The aim of the present study was to investigate autonomic nervous system functions in Behçt's patients by analyzing electrodermal activities. A total of 16 patients and 16 healthy volunteers were accepted for the study. Skin potential recordings were taken at room temperature in a quiet place within a Faraday's cage. The mean values of basal skin potentials and skin potential responses in the patients' group were reduced when compared with those of the control group ( p=0.0001). There was no difference between the groups regarding the mean values of latency ( p=0.09). The findings suggest that electrodermal activities may reflect autonomic nervous system dysfunction in Behçet's patients, and the measurement of electrodermal activities may be useful for the assessment of autonomic nervous system involvement in Behçet's disease.