The work was aimed at evaluating the influence of a number of criteria related to the tumor itself and the general characteristics of the patient on the complexity of nephron-sparing surgery and developing an original comprehensive methodology for assessing the complexity of the nephron-sparing surgery of kidney tumors. We evaluated the criteria for the operation complexity taking into account the results of nephron-sparing surgery treatment of 701 patients with kidneys tumors. The creation of an original scale for assessing the complexity of nephron-sparing surgery is not an alternative to the most popular nephrometry systems in the world, but it reflects current trends in the development of kidney tumors treatment – using nephron-sparing surgery for the most complex tumors (for intravenous invasion, multifocal tumors, tumor localization in the kidney sinus, and relapse of the neoplasm) in patients with imperative indications. Such a scale for assessing the complexity of nephron-sparing surgery allowed us considering not only new factors related to the properties of the tumor, but also individual characteristics of the patient.