Standard indices of renal function, i.e. creatinine, glomerular filtration rate (GFR) and endogenous creatinine clearance, still fail to accurately characterise disease processes in kidneys and are not sufficient for proper therapy selection, efficacy prediction and treatment efficacy monitoring for renal diseases. Therefore, markers that allow for an inexpensive, easy and reproducible kidney function assessment should be sought. Lysosomal exoglycosidases, such as N-acetyl-β-D-hexosaminidase (HEX), its isoenzymes A (HEX A) and B (HEX B), α-fucosidase (FUC), β-galactosidase (GAL), β-glucuronidase (GLU) and α-mannosidase (MAN), excreted in minimal amounts in the urine of healthy children and adolescents, yet showing a significant increase in pathological conditions, may be useful in the diagnosis of kidney disease. Such conclusions were a result of our research on the activity of lysosomal exoglycosidases in the urine of healthy children and adolescents compared to children and adolescents with hypertension, ureteropelvic junction obstruction, and congenital or acquired solitary functioning kidney, as well as based on the findings on the urinary activity of lysosomal exoglycosidases in children and adolescents with various kidney diseases, which were obtained by other authors.