Development and progression of chronic kidney disease (CKD) in patients with renal cell carcinoma (RCC) after radical nephrectomy remains an  extremely pressing contemporary issue. Postoperative changes of the ultrasound resistance index (RI) in the contralateral kidney not affected by the tumor after surgical treatment of RCC, as well as correlations between changes in IR and in glomerular filtration rate (GFR) remain far from being comprehensively investigated. The RI changes in the parenchyma of the intact (unaffected by the tumor) kidney before and after surgical treatment for RCC, and establishing correlations between RI changes and creatinine-dependent GFR remain unexplored issues.