Acute small bowel obstruction remains one of the most challenging nosologies in emergency surgery, leading to a pronounced imbalance between lipid peroxidation and the antioxidant defense system. We aimed to study changes in the anti- and prooxidant status of serum and small intestine wall in an experiment modeling acute small bowel obstruction. The control group included 11 rats, and the main group included 42 rats (simulation of mechanical bowel obstruction on day 1 was conducted in 14 rats, on day 2 – in 12 rats, on day 3 – in 16 rats). Acute small bowel obstruction was modeled by ligation. Serum analysis and removal of the small intestinal wall were performed on days 1, 2, and 3. Indicators of lipid peroxidation and antioxidant protection were determined by the spectrophotometric method, and the imbalance between lipid peroxidation and antioxidant protection gradually increased from 1 to 3 days of observation. On day 3, the low level of aldehyde increased 1.3 times, and the level of superoxide dismutase decreased 1.2 times compared to the control group. Pathophysiological changes in the wall of the small intestine are caused by the activation of lipid peroxidation and the exhaustion antioxidant protection, whereby the degree of their severity increases depending on the increase in time from the moment of modeling of acute obstruction of the small intestine.