Relevance. The Baker's cyst is the most numerous group of benign neoplasms of the popliteal region. The anatomical feature of the location, the vagueness of the etiology and pathogenesis leads to the lack of a single point of view on the tactics of treating popliteal cysts. In modern medical technologies, the method of local laser hyperthermia is often used, when the denaturing of collagen forming the basis of a tissue or an organ is based on surgical treatment. Since this technique does not have direct thermal control over the course of manipulation, it becomes necessary to strictly dosage controlled photocoagulation. Objectives of the study: to determine the optimal energy and time parameters of direct contact laser action on the wall of the Baker cyst in the simulation of its exo-vivo photocoagulation. Materials and methods of research. In the experiment we used a wall sample of Baker's cyst, obtained as a result of open extirpation of the cyst. The material was divided into 5 roughly equal in size and mass fragments. The first of them, without any physical effects, was immediately placed in a 10% formalin solution. For all other parts of the preparation, laser irradiation was carried out in a stationary manner with a surface contact of the optical fiber with the synovial layer of the samples. The effect on the fragment was carried out in a constant mode of the light flux with a wavelength of 1.47 μm. Results. The macroscopic and microscopic transformations that occur in the tissues of the wall of the Baker cyst were studied, with an output power of 5 and 10 W. Two series of experiments were conducted lasting 5 and 10 seconds. On the surface of the synovial membrane of the wall of Baker's cyst, the effect in the form of point carbonation was observed in all samples subjected to laser treatment. When a microscopic study of a drug not exposed to laser radiation, the synovial membrane was only loosened. In the fragment subjected to the contact action of 10 W laser radiation for 10 seconds, the focus of necrosis of the synovium and surface layers of collagen structures without a perifocal cell reaction is histologically determined. In all other samples, after laser photocoagulation, a focal destruction of the synovial membrane with a pronounced interstitial edema was determined in the histological study. Focal fragmentation of the surface fibers was detected near the loose loose collagen layers. Conclusions.The effect of high-energy laser radiation of 1.47 μm on the wall of the Baker cyst in all series of experiments did not lead to its total coagulation necrosis even in the direct irradiation zone. Considering the duration of the cyst of the energy exposure of the irradiation sufficient for the destruction of the wall, and also the small area of exposure of the laser irradiation to the face lightguide, it is evident that a considerable amount of time will be required for complete coagulation of the formation.