Th e aim of this study was to determine the antibiotic sensitivity to Escherichia coli and Klebsiella pneumoniae strains isolated in Microbiology Laboratory of Çankırı State Hospital between January 2007 - March 2008. Urine, sputum and wound samples which send from various clinics were inoculated both sheep blood agar and EMB agar; and blood samples added to biphasic blood culture medium (Biomeriux) in accordance with routine procedures. Sputum and wound samples were analysed for the presence or absence of leukocytes with gram staining. Microorganisms identification have been realized according to the biochemical properties. Micoorganisms can not be identified with convational methods were determined with semi automized systems (Biomeriux; Api 20E). To some antimicrobial agents, antimicrobial susceptility was been made by Keurby Bauer disk diff usion testing according to the recommendations of Clinical Laboratory Standards Institute (CLSI). Extended spectrum beta-lactamase production of Escherichia coli and Klebsiella pneumoniae strains were evaluated by double disk synergy method. In this time period 3156 urine, 703 sputum, 255 wound and 246 blood culture samples were sent to our laboratory. In 876 sample (20.9%) at least one bacteria was been isolated of total of the 4360 samples. Escherichia coli isolated from 347 sample and Klebsiella pneumoniae isolated from 91 sample. Th e extended spectrum beta-lactamase production rate was 18.8 % (n=73) in Escherichia coli, and 21.9% (n=20) in Klebsiella pneumoniae. Lower susceptibilty rates were determined among Escherichia coli and Klebsiella pneumoniae strains especially against amoxicillin/clavulonic acid and cefalosporins which are oft en used as empirical antimicrobials in various infections. Karbapenem resistance was shown only in a one Escherichia coli strain; karbapenem's still appear to be the most eff ective antibiotic against all tested bacteria.