The role of interactions between tumor cells and autologous immunocompetent cells, the impact on the modulation of the activity of T CD4⁺ and CD8⁺ lymphocytes, as well as the influence on the regulation and determination of antitumor cellular immune response in patients with head and neck squamous cell carcinomas (HNSCC) is not completely clear. The aim of this study was to analyze early and late activation antigens expression on T cells subpopulations modified under the influence of the presence of cancer cells to investigate the regulatory mechanisms of the local cellular immune response in carcinoma of the larynx. Cytofluorymetric analysis of the early (CD69⁺, CD71⁺) and late activation markers (CD25⁺ _high, CD26⁺, HLA/DR⁺) expression on T CD3⁺CD4⁺ and CD3⁺CD8⁺ cells subpopulations in mixed cellular cultures of freshly isolated tumor cells (MLTMC) and non-cancerous normal epithelial cells (MLNCC) with immunocompetent cells was performed in 55 cases of squamous cell laryngeal carcinoma. The whole peripheral blood concentrations of IL-10 and IFN-γ in 21 h and 72 h of experiments were also measured by ELISA. The relationships between the activation markers expression depending on the type of cells used in co-cultures, as well as the level of secreted cytokines, were investigated. Our work has revealed a statistically significant dependence of cytofluorymetric results on the presence of TMC or NCC in mixed cellular cultures. Increased expression of CD69⁺, CD71⁺ and CD25⁺ _high, CD26⁺, HLA/DR⁺ antigens on T CD3⁺CD4⁺ and CD3⁺CD8⁺ cells was higher in MLTMC cultures, in comparison with MLNCC. We demonstrated negative significant relationships of IFN-γ and IL-10 secretion with regard to CD4⁺CD69⁺, CD8⁺CD69⁺, CD4⁺CD71⁺, CD8⁺CD71⁺ antigens expression in 21 h of experiments without mitogenic stimulation. Furthermore, this study revealed negative significant relationships of IFN-g secretion with regard to CD4⁺HLA/DR⁺ and CD8⁺HLA/DR⁺ as well as between IL-10 concentration and CD4⁺HLA/DR⁺ in trials without PHA stimulation. Our findings have confirmed a key role for tumor cells in determining the function of T cells involved in the immunological processes and impact of neoplastic cells on modulating the activity of T CD4⁺ and CD8⁺ lymphocytes in laryngeal carcinoma. (Folia Histochemica et Cytobiologica 2011; Vol. 49, No. 4, pp. 579–592)