The importance of urinary tract infections relies in their relatively high incidence, as well as in their numerous and complicated problems of diagnosis and treatment. Considering the high incidence of urinary infections we made a study in order to determine the antibiotic susceptibility of Enterobacteriaceae strains isolated from urocultures of ambulatory patients and to precise the resistance phenotypes of these strains. We studied enterobacteriaceae strains isolated from 1889 urocultures of ambulatory patients between January - December 2004. From 1889 urocultures 431 were positive, the most common strains were E. coli - 350 strains (81.21%). We observed a constant lowering of the sensitivity of E. coli strains to many antimicrobial agents which draws attention to on the importance of monitoring antibiotics prescriptions. We must draw a signal about the presence of some ESBL (beta-lactamase with extended spectrum) strains (1 E. coli strain and 3 Klebsiella pneumoniae strains), which are usually isolated in hospital, due to empiric, irrational and abusive usage of antibiotics, without doing the antibiograms.