The present study was designed to evaluate the plasma markers of reactive oxygen species (ROS) activity and cytokines, and their relationship with thiol redox status of basketball players during training. Sixteen professional players of the Polish Basketball Extraleague participated in the study. The study was performed during the preparatory period and the play-off round. Markers of ROS activity (lipid peroxidation TBARS, protein carbonylation PC) and reduced glutathione (GSH) demonstrated regularity over time, i.e. TBARS, PC and GSH were elevated at the beginning and decreased at the end of training periods. Oxidized glutathione (GSSG) was not affected by exercise training. Thiol redox status (GSHtotal-2GSSG/GSSG) correlated with TBARS and PC in both training periods. The level of interleukin-6 (IL-6) was increased and positively correlated with thiol redox (r=0.423) in the preparatory period, whereas tumor necrosis factor α (TNFα) was increased and inversely correlated with thiol redox (r=-0.509) in the play-off round. The present study showed significant shifts in markers of ROS activity, thiol redox status and inflammatory mediators (IL-6, TNFα) following professional sport training as well as correlation between changes in thiol redox and cytokine response., A. Zembron-Lacny, M. Slowinska-Lisowska, A. Ziemba., and Obsahuje bibliografii a bibliografické odkazy