Comparative analysis of relationships between individual peculiarities of the structure of nephrons in intact and hydronephrotic right rabbit kidneys, on one hand, and the degree of expression of nephrotoxicity of gentamicin with respect to the only intact and as well hydronephrotic left kidney, on the other hand, was undertaken. Damage of the kidney by this antibiotic is more expressed in rabbits with smaller diameter of distal convoluted tubules of nephrons and smaller size of the cells lining their lumen. These peculiarities of the structure of nephrons lead to predisposition to the gentamicin-induced nephropathy in intact rabbits to a higher degree than in animals with hydronephrosis. The method of predicting individual predisposition to gentamicin-induced nephropathy has been patented (No. 7722 of 13.10.2005).