The aim of the study was to answer the question whether the serum level and the urine level of N-acetyl-beta-D-glucosaminidase (NAG) could be the indicator of liver and kidney lesions, and the indicator of the stage of the lesions, in cases of endotoxemia and endotoxin shock. The authors performed the experiment using 60 rabbits as experimental animals. The animals were divided into six groups (10 rabbits in each group); control animals received an equal volume (1.0 ml/kg of body weight) of physiological saline solution. Endotoxin (Lipopolysaccharide E. coli 055 B-5) in doses of 20, 40, 60, 80, and 100 micrograms/kg of body weight were administered in a single intravenous injection to each animal of I-V experimental groups. Using endotoxin in that dose of application, the authors provoked different stages of endotoxemia on the rabbits in the first four experimental groups, and the endotoxin shock on the rabbits of the fifth experimental group. After 18 hours, the rabbits were decapitated, and the levels of NAG in serum, urine, kidney and liver tissues determined. The results showed that the serum increase of NAG activity is caused not only by the lesions of kidney parenchyma, but by the lesions of liver parenchyma too, in the cases of endotoxemia and endotoxin-produced shock; the increase is statistically significant. Urine increase of NAG activity is significant even in cases in which the authors administered very low doses of endotoxin (20 micrograms/kg of body weight), so it can be said that urine NAG activity is a very good indicator of early kidney parenchyma lesions. But, the urine increase of NAG activity is (absolutely) in correlation with the dose of administered endotoxin, so it can be said that urine activity of NAG is the indicator of stage of kidney lesions in cases of endotoxemia and endotoxin-provoked shock.