The study examined the activity of enzymes in the polyol pathway and the status of free radical processes in the kidneys of rats subjected to different dietary protein and sucrose levels. It was found that the kidneys of animals consuming a highsucrose diet, irrespective of protein content, exhibited the highest increase in the activity of polyol pathway enzymes, namely aldose reductase and sorbitol dehydrogenase. Consumption of a high-sucrose diet enhances the generation of O2 •- in the kidneys by almost twofold, and hydroxyl radical by over fourfold compared to control indicators. This is accompanied by a twofold increase in the content of TBARS-active products and a threefold increase in the content of carbonyl derivatives of proteins, against the background of a decrease in the content of free thiol groups in proteins. The pronounced generation of hydroxyl radicals, accumulation of TBARS-active products, and reduction in the content of free SH-groups in proteins are characteristic of animals that consumed a high-sucrose diet in the context of dietary protein deficiency. It has been demonstrated that excessive sucrose consumption is a critical factor, influencing the activity of enzymes in the polyol pathway and the intensity of free radical processes. The obtained results may be considered as predisposing factors for disruptions in the structural and functional organization of the kidneys under conditions of nutrient imbalance.