AIM Assessment of the etiology of urinary tract infections and pathogen drug sensitivity in hospitalized children. MATERIALS AND METHODS We analyzed 156 medical records of patients admitted to the Clinical Department of Pediatrics, Bielański Hospital in Warsaw in 2012, with a suspected UTI. Positive urine culture results were found in 113 (72.4%) children (68; 60.2% of girls and 45; 39.8% of boys), aged from 2 months to 17.9 years (the average age was 2 years and 3 months). RESULTS E. coli was the most frequent isolated pathogen - 92.0% of patients (104/113). The greatest sensitivity of pathogens showed to cephalosporins of the second and third generation (80.5-90.3%). The sensitivity to amoxicillin with clavulanic acid was 71.7% and 41.6% for ampicillin. The length of hospital stay and treatment ranged from 2 to 16 days (average 8.6 days). In 60.2% (68/113) of patients were treated with second cephalosporin, in 17.7% (20/113) with third generation cephalosporins. Only 11.5% of them (13/113) received amoxicillin with clavulanic acid. Before the treatment, 69.9% (79/113) of children had a fever from 38 up to 41,7ºC, and the fever persisted for the average of 2.5 days (1-8 days). We found significantly higher levels of CRP in children aged between 2-4 in comparison to other age groups (p= 0.0290). In 44.2% (50/113) of children the cystourethrography was performed and in 22% (11/50) cases we recognized a unilateral or bilateral vesicoureteral-ureter of a I to IV degree, on one or both sides. CONCLUSION The most common etiological agent of UTIs in children remains E. coli. The sensitivity of urinary pathogens to the commonly used antibiotics is still high, however, finds a large percentage of strains resistant to ampicillin and to amoxicillin with clavulanic acid. The antibiotic recommended for empiric therapy of UTIs in children should be cephalosporins, if there is such a possibility, the treatment should be based on drug sensitivity tests of the organisms grown. Because of the relatively long hospitalization of children with UTIs and the possibility of hospital complications, sequential treatment should also be considered sequential.