ABSTRACT The purpose of this work is to study the content of macronutrients in the tissues with oncourological pathology. Methods: Clinical examination material of 279 people was used in the work, 229 of them were men (82%) and 50 were women (18%). Elemental analysis of oxygen, carbon, calcium, nitrogen and sulfur was carried out using a detector to record the spectra of characteristic X-ray radiation (EPAX company), which were integrated with "Quanta 600 FEG" scanning electron microscope. Results: with prostate cancer, the oxygen content decreased, so during stage 1, the oxygen content decreased by 36.8% among middle-aged patients, and by 38.6% among elderly patients, stage 2 - by 32.4% and 28.9%, stage 3 - by 34.1% and 34.2%, and stage 4 - by 30.9% and 35.1%. The nitrogen content changed insignificantly, carbon and sulfur decreased. The calcium index among middle-aged patients with stage 1 prostate cancer increases by 10.6, and by 10.8 times among the elderly, while it is absent among the patients with stage 2, 3 and 4. The nitrogen content among the patients with renal pathology did not change significantly, but there was a tendency of carbon, calcium, and sulfur increase and oxygen decrease. When they studied the level of macronutrients in bladder cancer, there was a tendency to nitrogen and carbon level increase, and in the groups of stage 1 and 2 patients, the content of calcium and sulfur increased by 12.5 and 3.8 times, respectively, and oxygen was also reduced. Conclusions: we found that all groups demonstrated oxygen content decrease, most pronounced among stage 2 patients with bladder cancer - 49.5%, which leads to tissue hypoxia in the studied organs. The nitrogen and carbon content varied slightly. The content of calcium and sulfur increases among the patients of all studied groups.