OBJECTIVE The aim of the study was to investigate the effect of hyperbaric oxygen-preconditioning (HBO-PC) and ozone-preconditioning (O3-PC) on oxidative/nitrosative stress induced by tourniquet ischemia/reperfusion (I/R) in rat skeletal muscle. METHODS Thirty-two Wistar-Albino-type male rats included in the study were divided into four groups of equal number: 1) sham operation, 2) I/R, 3) I/R+HBO-PC, or 4) I/R+O3-PC. One session of 3-4 L/min 100% oxygenation for 60 min at 3 absolute atmosphere (ATA) was defined as one dose of HBO; in total, 7 doses of HBO-PC were administered before ischemia. One dose of O3 comprised 0.7 mg/kg ozone/oxygen mixture, administered intraperitoneally; a total of 4 doses of O3-PC were administered before ischemia. The I/R model was performed in anesthetized rats by clipping right femoral artery to induce 2 h ischemia followed by 22 h of reperfusion. The right gastrocnemius muscle and venous blood samples were harvested. Tissue was assayed for levels of malondialdehyde (MDA), inducible nitric oxide synthase (iNOS), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px). Serum was assayed to measure the level of nitrite-nitrate (NOx). RESULTS Tissue MDA level, SOD activity, and serum NOx level were increased, whereas GSHPx was decreased in the I/R group. MDA and NOx levels were decreased, whereas GSH-Px activity was increased in both the I/R+HBO-PC and I/R+O3-PC groups. SOD activity was increased in the I/R+O3-PC group, but did not change significantly in the I/R+HBO-PC group. iNOS staining score and intensity were lower in the I/R+HBO-PC and I/R+O3-PC groups than I/R group. CONCLUSIONS Both O3-PC and HBO-PC reduced tissue lipid peroxidation, NOx levels, and iNOS staining scores in the experimental I/R model. Our data suggest that HBO-PC and O3-PC protect against oxidative/nitrosative stress induced by I/R in rat skeletal muscle.