The aim of this study was to evaluate the tear nitric oxide (NO) level in patients with Behçet's disease and to compare it with that in healthy subjects. MATERIAL AND METHODS. The subjects were divided into 3 groups: the active disease, inactive disease, and control groups. NO concentrations were determined by a nitrate/nitrite colorimetric assay kit and measured spectrophotometrically at 540 nm. RESULTS. The tear nitrate/nitrite levels were 0.06 nmol/μL (SD, 0.05) in the active disease group, 0.05 nmol/μL (SD, 0.05) in the inactive disease group, and 0.02 nmol/μL (SD, 0.01) in the control group. The tear nitrate/nitrite levels of both active and inactive groups were higher than those of the control group (P=0.001 and P=0.047, respectively), but there was no significant difference between the active and inactive groups. CONCLUSION. Our results demonstrated that the tear NO levels were elevated in the patients with Behçet's disease. We imply that a better understanding of NO function in the pathogenesis of Behçet uveitis is necessary to develop new therapies based on the inhibitors of NO synthases.