The aim of this study is to identify the most common bacteria that cause UTI and to rationalize antibiotic guidelines for UTI to optimize outcome and to minimize resistance at a reasonable cost to the patient and the community. In a clinical trial to identify the sensitivity/resistance pattern of ten different antimicrobial agents commonly used in the treatment of urinary tract infections (UTI) in El Batnan Medical Center (BMC), Tobruk-Libya, during 2003 and2004. A total of 773 midstream urine samples from outpatients and inpatients attended Central Lab in El Batnan Medical Center (BMC) clinically suspected as having UTI, were examined for microbiological confirmation and pattern of antibiotic susceptibility by disc diffusion method. By using direct smear microscopy and routine culture methods, 8 different bacterial species were isolated from only 262 (33.9%). The remaining 511 (66.1%) of cases showed no bacterial growth.Bacteriological examination of the urine samples showed Escherichia coli strains isolated in 106 (40.4%) of cases with UTI, Klebsiella in 59 (22.5%), Staph epidermidis in 35 (13.3%), Staph aureus in 32 (12.2%), Proteus spp in 12 (4.5%), while 8 (3%), 6 (2.3%), 4 (1.5%) of cases showed Pseudomonas, Entrococci and Corynebacteria respectively. The study of the antimicrobial sensitivity/resistance pattern of ten different antimicrobial agents commonly selected in the treatment of UTIs, indicated that the antimicrobial drug of choice for treating UTI caused by Escherichia coli strains, Klebsiella, Staph. epidermidis, Staph. aureus, and Proteus spp. should include Ciprofloxacin (80.2% sensitivity), or Amoxicillin (70.2% sensitivity), or Nitrofurantion (64.5% sensitivity), or Ceftriaxone (61.8% sensitivity). Meanwhile, for treating UTI produced by Entrococci, the antimicrobial drug of choice is Amoxicillin (70.2% sensitivity), Naldixic acid (60.3% sensitivity), and Ampicillin (9.2% sensitivity), while for treating Pseudomonas spp, the drug of choice should be member of Fluoroquines group as Ciprofloxacin (80.2% sensitivity), and Sulphamethoxazol + Trimethoprim (Co-trimoxazole) (26.3% sensitivity).