Behcet disease (BD) is a systemic inflammatory disease of the unknown etiology. There is however, some evidence to suggest that immunological abnormalities are important in its pathogenesis, furthermore several T-cell abnormalities which may be quite relevant to autoimmune origin of the disease have been described. We report here our study of T-cell subsets, B and NK cells in 68 patients with BD in comparison to 30 normal controls, by monoclonal antibodies against CD3 (pan T-cell), CD4 (Helper) CD8 (Suppressor/cytotoxic), CD22 (B-cell) and CD16 (NK-cell) markers. The results show the increase (P=0.008) of T (CD3), T (CD4) (P<0.000001) and decrease of T (CD8) (P<0.000001) and reduction in ratio of CD4/CD8 cells (P<0.000001), but any alteration in B and NK cells number were not seen. In patients with BD 69.8% negative PPD test and above results suggests that the cellular immunity in these patients is anergic, which may be an important etiological factor.