Although tumour necrosis factor α (TNF-α) and interleukin 6 (IL-6) can stimulate each others activity and induce similar effects on distinct cells, soluble TNF-receptors (sTNF-RI and sTNF-RII) and soluble IL-6 receptor, exhibit significant differences in their functional activity.In this study the author investigated the concentrations of sTNF-Rs and sIL-6R in the culture supernatants of PMNs and in the serum obtained from breast cancer patients. Soluble TNF receptors in patients before treatment were higher than in control and decreased following the surgery treatment. Soluble IL-6 receptor was decreased in patients before treatment and elevated following the surgery treatment. Sera from patients presented increased the levels of sTNF-Rs and sIL-6R with respect to control. Chemotherapy treatment resulted in a decrease in the serum levels of sTNF-Rs and sIL-6R. There was a correlation between the amounts of sIL-6R in the culture supernatants of PMNs and the serum levels.Results obtained confirm the effective participation of PMNs in the immune reactions to tumour.