We examined 20 children in age from 6 till 18 years old with recurrent urinary tract infection (rUTI). The control group were 15 healthy volunteers in age from 19 till 23 years old. In all cases nitrogen oxide concentration was designated in supernatant of 48 hours leukocytes culture with using colorimetric method with Griess reagent described by Ding. The spontaneous and LPS stimulated ability to nitrogen oxide production in full blood was estimated. The nitrogen oxide index was counted from the difference of concentration of inducated and stimulated nitrogen oxide. The defective response of the leukocytes of full blood to LPS-stimulation for nitrogen oxide productionin aggravation also in remission in children with rUTI and with rUTI in age till 5 years old and above 5 years old comparing to healthy ones.