AIM: This study aimed to determine the content of matrix metalloproteinase-9 (MMP-9) in the aqueous humor (AH) of the eyes in children with uveitis and its role during the disease.
 MATERIAL AND METHODS: Twenty children (20 eyes with uveitis) aged from 3 to 16 yr (11.253.43 yr on average) and three children with congenital cataract from the control group were examined. The concentration of MMP-9 was determined by enzyme-linked immunosorbent assay (ELISA) using the ELISA kit for MMP-9 (Cloud-Clone Corp, USA). The optical density of the samples was measured using a multifunctional photometer for Synergy microplates (BioTek, USA).
 RESULTS: Children with uveitis had a higher content of MMP-9 in the AH than children in the control group (p=0.006). An increase in the content of MMP-9 in the AH of the eyes was correlated with an increase in the degree of proliferative changes in the eye.
 CONCLUSION: The concentration of MMP-9 in the AH of the eyes correlates with the severity of proliferation, and its measurement can be used to assess the severity of the inflammatory process in the eye.