Recently it was shown that oxidative stress has a negative influence on immunological response. The aim of the study was to investigate the influence of N-acetylcysteine on intracellular oxidative stress and cytokine synthesis in peripheral blood lymphocytes in children with end stage renal disease (ESRD). MATERIAL AND METHODS. We examined 25 children (age 2-16 ys.) with ESRD. To determine oxidative stress we used dihydrorhodamine 123 (DHR). Intracellular oxidation of DHR in T. lymphocytes reflected intracellular oxidative stress within cells. The intracellular synthesis of cytokines (IL-2, IFN-r, IL-4, IL-6) was detected with flow cytometty RESULTS. We found lower intracellular stress and higher cytokines synthesis after incubation with N-acetylcysteine (NA C) in all subpopulations of lymphocytes. CONCLUSIONS. Our results shows that patients with ESRD present increased oxidative stress in T lymphocytes which may lead to decreased cytokines synthesis and abnormal immune response. NAC has favorable influence on these abnormalities.