Background: Vascular endothelial dysfunction represents the major pathogenesis abnormalities in Behçet's disease (BD). Homocysteine (Hcy), a non-protein-forming amino acid was proposed to be involved in the inflammatory process, and increasing homocysteine concentrations in ischemia may lead to leukocyte recruitment in the affected tissue.  Aim: to find out the possible relation between homocysteine (HCY) serum level and ocular involvement in Behçet's disease (BD) patients. Methods: 30 BD patients as classified by the new International Behçet's Disease Criteria (25 males and 5 females with the age mean 33.83 ± 9.41years) and 20 healthy control subjects (age and sex matched) were included. The patients were divided into two groups: those with BD and eye involvement (n=24) and those without ocular involvement (n= 6).  Results:  The mean serum HCY values in BD patients were substantially greater than in healthy controls (37.87 ± 10.31 and 21.80 ± 5.47 mmol/L, respectively; P <0.001). HCY readings were higher in patients with eye involvement than in patients who did not have eye involvement. (38.91 ± 10.13 and 33.72 ± 10.9 mmol/L, respectively) yet, these differences did not reach the level of statistical significance (P>0.278). Conclusion: Serum HCY level is increased in BD. No association was found between HCY levels and eye involvement. Because hyperHCY is a treatable risk factor, measurement and monitoring of HCY levels may be a valuable index in the investigation, management and improving the outcome of patients with BD.