The influence of stress and 1.4‑naphtoquinone derivative on the background of low intensity X‑ray irradiation on lipid peroxidation processes and NO‑synthase system in mucous membranes of stomach, small and large intestine in rats was investigated. It was established that the effect of stress on the background of X‑ray irradiation (total dose 20 sGy) caused increase of TBA-active compounds level, activity of myeloperoxidase and iNOS in mucous membranes of digestive organs compared to relevant indices under the effect of X‑ray irradiation. Peculiarities of<br />antioxidant effect of 1.4‑naphtoquinone derivative on the background of X-ray irradiation in investigated organs are<br />shown.