Introduction: The aim of the presented study was to determine the activity of chemotrypsine (CT) and leucinaminopeptidase (LA) in urine of children with glomerulonephritis (GN). Material and methods: Was carried out investigation of 40 children with acute GN and nephrotic syndrome, period of relapse and remission. The age of children was in range from 3 to 17 years. The control group comprise 15 conventionally healthy children. Results: In initial stage of acute GN with children with steroid-sensitive nephrotic syndrome was mentioned significant increasing activity of CT in urine in 2.2 fold (0.86 ± 0.16 nM/s mM creatinine, p < 0.01) compared to control group (0.39 ± 0.06 nM/s mM creatinine). In patients with steroid-resistant nephrotic syndrome acute GN at the initial stage the activity of CT in urine increased only in 1.5 fold (0.57 ± 0.12 nM/s mM creatinine) compared to control group. In remission was mentioned decreasing of enzymes in urine, excluding patients with acute GN with steroid-resistant nephrotic syndrome, in which the activity of CT in urine increased in 2.6 fold (1.03 ± 0.09 nM/s mM creatinine, p < 0.05), compared to control group. In children with steroid-resistant nephrotic syndrome, acute GN, in initial stage of the disease, the activity of LA in urine increased in 2.7 fold (p < 0.01) compared to control group (0.68 ± 0.05 nM/s mM creatinine). In remission was mentioned decreasing of activity of LA in urine (0.57 ± 0.14 nM/s mM creatinine) compared to control. Conclusions: The investigation of proteolytic enzymes in urine in children with GN is early diagnostic marker of activity, severity as well as outcome of the disease.