Prosthetic reconstruction of the pelvic floor via vaginal access is a common and effective approach to treating the obvious forms of pelvic organ prolapse. The specificity of this technology is an abundance of blind steps when a surgeon has no direct visual control of manipulations – all is based on tactile sensations and spatial sense. Under these conditions, a thorough knowledge is a key condition for surgical safety. Objective. To identify main anatomic landmarks for safe implantation of mesh endoprostheses via vaginal access, by applying harpoon fixators, and to determine the optimal sizes of endoprostheses to achieve the necessary result in most patients. Subjects and methods. A total of 120 women underwent radiographic examination (pelvic bone X-ray, small pelvis computed tomography (CT), and small pelvis CT angiography. The examination revealed no statistically significant correlation between the patients’ anthropometric measurements (height, weight) and the distance between the obturator foramens and ischial spines. Results. These distances were found to vary minimally. The interspinous distance was 108.03±5.91 mm (range, 96.14—124.04 mm); the interobturator foramina distance was 61.09±4.71 mm (range, 49.20 —71.67 mm). Examination of angiographic images showed that on sacrospinal fixation of a prosthesis, the points of injection should be offset by at least 1.5—2.5 cm from the ischial spine and be strictly within the sacrospinous ligament in order to prevent damage to vascular structures. The safe zone in the obturator foramen is in its inferomedial corner. Conclusion. The findings could determine the optimal size of an endoprosthesis. Thus, for the prevention of obstruction of the rectum and the neck of the urinary bladder on troacar-free application of meshes, the optimal length of the interspinous and interobturator parts of implantation should be 15 and 10 cm, respectively.