Background. Upper urinary tract infections (UTIs) are common in children, but attitudes toward the diagnosis and the acute treatment are heterogeneous among pediatricians and pediatric nephrologists. In effect the choice of antibiotic regimens is largely empirical and based on local practice, with no rationale for the choice of oral or parenteral administration. A retrospective study (1993-97) showed that in 1333 (36 % M) hospitalized children because of a prove UTI, parenteral antibiotic was given initially to 756 (57.2%) of the population studied.