In the present study the expression of tumor-promoting B cell-activating factor (BAFF), a member of the tumor necrosis factor superfamily (TNF) in neutrophils from oral cavity cancer patients, was examined by real-time PCR. For the purpose of comparison, the expression of BAFF protein was assessed in autologous peripheral blood mononuclear cells (PBMCs). An important question of this study has also been to explain the role of NF-κB in the induction of BAFF molecule. The increased expression of BAFF at the mRNA and protein levels in neutrophils and mononuclear cells of patients before and after treatment were accompanied by the increased expression of phospho-IκB protein level. Demonstrated excessive expression and secretion of BAFF by examined leukocytes suggest a tumor-promoting activity of those cells in oral cavity cancer patients. The overexpression of BAFF, observed at mRNA and protein levels in PMNs and PBMCs, as well as the secretion of soluble form of sBAFF by these cells, accompany the increased concentrations of sBAFF in the serum of patients. Observations above suggest that the modulation of BAFF molecules in examined leukocytes and the levels thereof in the serum may have future implications for immunotherapy of oral cavity cancer patients.