The article presents data on structural and functional changes of the mucous membrane of the uterine tube in the dynamics of two-, four-and six-week exposure to nalbuphine. The material of the study were sexually mature rats-females of the line "Wistar" in the amount of 26 animals weighing 180-220 g, aged 3.5-4 months. Animals were injected with nalbuphine intramuscularly, daily, once a day, at the one-time interval. Histological preparations were prepared according to the conventional method. The animals were kept in a vivarium, the work was carried out following the "Rules of work using experimental animals". Before sampling, the animals were primed with an intraperitoneal injection of thiopental (at a rate of 25 mg/kg), then an anterior abdominal wall was opened, followed by removal of the fallopian tube. During the experimental research, changes in the structure of the mucous membrane of the fallopian tube were established. The first signs were found within 2 weeks of the experimental effect of nalbuphine: swelling of the mucous membrane of the fallopian tube, slight smoothing of the folds and local desquamation of the epithelium, moderate infiltration of lymphocytes of the mucous membrane. Vascular microcirculatory vessels of the mucous membrane are slightly expanded. After 4 weeks of the experiment, degenerative and inflammatory changes in the uterine tube wall and manifested by swelling and polymorphocellular infiltration of the membranes of the wall of the test organ wall, an increase in the number of altered epitheliocytes, vessels are hyperemic, overflowing with aggregated erythrocytes, sometimes containing neutrophilic granulocytes and lymphocytes. After 6 weeks of administration of nalbuphine, destructive changes in the cells of the mucous membrane of the fallopian tube and the links of its hemomicrocirculatory bed accrue, manifested by desquamation of the epithelium of the mucous membrane, infiltration of the mucous membrane by lymphocytes, there is an expansion of the lumen of the vessels of the microcirculatory bed and filling the lumen of the blood plasma, there are lashes of different heights, the characteristic grouping of them into conglomerates.