Soluble cytokine receptors by binding to circulating cytokines play an important role in the regulation of immune response of the host. Measurement of their release may be helpful in the evaluation of cytokine-mediated reactions in patients with cancer disease. Soluble tumor necrosis factor receptors (sTNF-Rs) in the culture supernatants of PMNs and in the sera obtained from patients with breast cancer were determined. The examinations were carried out before and after treatment involving surgery and chemotherapy. The highest concentrations of sTNFRp55 and sTNFRp75 were observed in the culture supernatants of PMNs from patients before any treatment, the lower concentrations of them were found in the supernatants of PMNs after treatment. Sera from breast cancer patients presented increased levels of sTNFRp55 and sTNFRp75. Surgery treatment resulted in higher concentrations of sTNFRp55 and sTNFRp75. Decreased sTNF-Rs serum levels were obtained in patients after adjuvant chemotherapy. Different ability of PMNs to the release of TNF-regulatory proteins-sTNFRs appears to confirm PMNs participation in TNF-mediated reactions of the host during malignant process via sTNF-Rs release.