The influence of the platelet-activating factor receptor-antagonist (BN 52021) and polyelectrolyte solution (PES) on the morphology and oxidant-antioxidant equilibrium in the gastrointestinal wall in hemorrhagic shock was examined in rats. The animals were divided into five groups: I — control, II — sham operation, III — untreated hemorrhagic shock lasting 75 minutes, IV — shock treated with PES, and V — shock treated with BN 52021 and PES. The most expressed morphological changes were found in the small intestine in group IV (shock treated with PES) and in group III (untreated shock). Morphological changes were well correlated with the malondialdehyde (MDA) level reflecting oxidative tissue injury and with the antioxidative potential: sulfhydryl compounds (-SH) level, and superoxide dismutase (SOD) activity. The signs of morphological and biochemical injury to the gastrointestinal tract in animals from group V (treated with BN 52021 and PES) were significantly less expressed than those in groups III and IV. The results suggest an essential role of PAF in oxygen radicals-mediated gastrointestinal injury and a beneficial effect of the early application of BN 52021 in hemorrhagic shock.