This study was performed to investigate serum levels of various cytokines and E-selectin in patients with Behcet's disease (BD) before and after treatment with interferon-alpha 2a (IFN-alpha). The study population consisted of 22 patients with active BD; 15 age- and sex-matched healthy adults served as the control group. IFN-alpha (3 million units subcutaneously) was given to all patients twice a week for 3 months. Twenty of twenty-two patients experienced clinical improvement with this therapy. Pre- and post-treatment serum levels of tumor necrosis factor-alpha (TNF-alpha), TNF-alpha 2-receptor (TNF alpha 2R), interleukin-2 (IL-2), IL-2 receptor (IL-2R), and E-selectin were measured by sandwich-type enzyme immunoassay. Baseline E-selectin, TNF-alpha, and TNF-alpha 2R levels of the patients were increased in comparison with the control group and post-treatment values. However, IL-2 and IL-2R levels did not change either with treatment or compared with the control group levels. In conclusion, these results confirm the previously described efficacy of IFN-alpha in the treatment of BD. Serum levels of TNF-alpha, TNF-alpha 2R, and E-selectin are prominently increased during active stage of the disease, indicating presence of immune system activation and endothelial injury/activation. Improvement of the pathological cytokinemia and endothelial disturbance accompany interferon-alpha-induced disease remission.