BACKGROUND To investigate the gene expression levels of interleukin 10 (IL10), IL18, interferon gamma (IFNG), IFN-gamma receptor (IFNGR), C-reactive protein (CRP), and heat shock protein 70 (HSP70) in patients with active Behçet's uveitis. MATERIAL AND METHODS Forty patients with Behçet's disease diagnosed according to the International Study Group criteria and 30 healthy individuals were included in the study. IL10, IL18, IFNG, IFNGR, CRP, and HSP70 gene expression levels were compared. RESULTS Expression levels of IL18, IFNG, IFNGR, and CRP were significantly higher in patients with active Behçet's uveitis than in control subjects (P<0.01 for all), whereas no significant differences were found in IL10 and HSP70 gene expression levels (P>0.01 for both). CONCLUSIONS IL18, IFNG, IFNGR, and CRP gene expression is significantly increased in active Behçet's uveitis. There was no significant difference between active Behçet's uveitis patients and controls in terms of IL10 and HSP70 gene expression levels. We conclude that drugs prescribed to Behçet's patients with active uveitis downregulate gene expression.