A retrospective study was performed in the Microbiology department of Reference laboratories of Iran, Research Center over a 4 year period (2002–2006). 4207 urine samples were examined, 476 (11%)of which revealed significant bacterial growth and were selected to determine the bacterial susceptibility to antibiotics with disk diffusion method (CLSI No: M2-A9) (disks manufactured by BD and Mast). Our study shows that E. coli (44.5%) and Klebsiella pneumoniae (8.5%) were the most predominant pathogens. E. coli revealed the highest susceptibility among oral antibiotics to Nitrofurantoin (76%) and the highest resistance to Carbenicillin (94%) and Ampicillin (89%). In total isolates: the highest susceptibility was to Imipenem (99%) and among oral antibiotics to Nitrofurantoin (70%) and the highest resistance to Carbenicillin (89%) and Ampicillin (84%) as shown in the table below. There is considerable resistance in bacterial UTI pathogens to Fluoroquinolones and co-trimoxazole and considerable sensitivity to Nitrofurantoin. We strongly recommend Nitrofurantoin as the drug of choice for empiric therapy of UTI.