Intense exercise (IE) causes damage to organs and tissues such as in the gastrointestinal tract, urinary, and brain. Even though IE is associated with dysfunctions in the female reproductive system, little is known about the mechanisms underlying its effects mainly on the non-pregnant uterus. We investigated the effects of intense and exhaustive exercise (IEE) program on the isolated uterine morphology, tissue responsiveness, and oxidation markers. Female C57Bl/6 mice (20 g), 3-month old, were acclimated for 5 days, and the oestrous cycle followed by daily vaginal smears. Animals were then allocated into 2 groups: control (CT) and exercised (EX) groups. EX group performed 2-consecutive days of a daily bout of treadmill running at 85% of its maximum running velocity (MV) until animal exhaustion. MV was determined by maximal incremental test (MIT 1) performed by all animals 24-h before the beginning of IEE program. Training responses were evaluated the time each animal took to reach exhaustion (TTE) and the MV, evaluated by the second MIT (MIT 2) performed 24-h after the end of the second exercise session. CT and EX animals were in the oestrous stage at the beginning of the exercise program. Tissue morphology was evaluated by histological analysis of 4-µm HE-stained uterine slices; tissue responsiveness was evaluated through concentration-isometric contractile response curves evoked by either KCl or carbachol (CCh) (de Jalon solution, T° 37°, pH 7.4, and 0.2 g basal tension); and uterus lipid peroxidation and protein oxidation were evaluated by MDA and carbonyl concentration measurements, respectively. IEE decreased animal physical performance as it caused 32 and 29% decreases in TTE and MV, respectively (N = 60), decreased the longitudinal muscular layer (from 79 ± 2 µm to 71.1± 2 µm, N = 6, p<0.05), impaired CCh-evoked contraction (increase in EC50 from 2.8 ± 1.2 to 18 ± 3 µM, and decrease in Emax from 1.7 ± 0.3 (N = 4) to 1.0 ± 0.2 g, (N = 6), p<0.05), but caused only strong trend to impair KCl-evoked contraction (increase in EC50 from 5.7 ± 1.3 to 9 ± 3 mM, and decrease in Emax from 1.4 ± 0.2 to 1.2 ± 0.16 g, N = 4-6 , p>0.05), reduced MDA concentration from 400 to 180 nmol/mL.g dry tissue (N = 5-6, p<0.05), without affecting the level of protein carbonyl (4 and 4.3 nmol/ mg protein, in CT and EX, respectively, N = 5-6, p>0.05,). Is concluded that C57BL/6 mice non-pregnant uterus is an important exercise-target, and displays important morpho-functional alterations in response to intense and exhaustive exercise which, nonetheless, are not related to signs of uterus oxidative stress, but may be well related to exercise-induced uterine dysfunction.