The purpose of this article was to establish changes of age, etiology, diagnostics and treatment for children, who were treated for urinary tract infection in Clinic of Children Diseases, Kaunas University of Medicine Hospital in 1994-1998 and 1999-2002. Seven hundred fifty children urinary tract infections were treated during the period of 1994-1998, and 673--during the period of 1999-2002. Female patients had urinary tract infection nearly five times more than male patients in other age groups. Rate of urinary tract infection in male patients under one year age was greater than in female in this age group (p=0.0001). Greater incidence of urinary tract infection in age group under one year age was established. The incidence among male patients with urinary tract infection grew from 37.8% to 64.0% (p=0.0001) and among female patients--from 9.6% to 18.1% (p<0.0001). More vesicoureteral refluxes (VUR) were diagnosed: 44 (7.8%) in period 1994-1998 and 52 (9.0%) in the period 1999-2002. More than one third of all VUR (36.5%) were diagnosed in age group under one year. The incidence of VUR in this group was greater for male than for female patients (p=0.015). More positive urinary culture for patients with pyelonephritis were in period 1999-2002 (74.6%) than in 1994-1998 (66.8%). The incidence of microorganisms was nearly the same. E. coli was found in 83.4% and in 83.9% of all positive urinary cultures. Sensitivity to the commonly used antibiotics was better (p<0.0001). Pyelonephritis mostly was treated with gentamycin.