Animal experiments demonstrate that gentamycin, kanamycin and carbenicillin affect lipid peroxidation in the kidneys. This can be registered by chemiluminescence of renal and urinary homogenates. This phenomenon was also used in functional examination of the kidneys in 161 neonates treated by antibiotics. The earliest renal dysfunctions due to nephrotoxicity were detected by chemoluminescence induced by ions of bivalent iron. The method is simple and rapid, this making it convenient in neonatal practice for detection of nephropathy before the symptoms presentation.