Existence of extended spectrum B-lactamase ( ESBL) genes plays an important role in causing B-lactam antibiotic resistance in the producing strains of these enzymes. The resistance of gram-negative bacteria, such as klebsiella pneumonia, to different antimicrobial agents, especially B-lactams and carbapenem, has increasingly been reported. This study was conducted to determine the prevalence of TEM-1 beta-lactamases in klebsiella pneumonia isolates through PCR method. In this descriptive-analytic study,120klebsiella pneumonia isolates collected from patients with Lung infection and UTI were subjected to bacteriological tests. The samples were cultured and identified according to standard methods. Then, frequency of the strains producing extended spectrum betalactamases was determined with Disk diffusion method. Byusing of kits, DNA was extracted and examined for the existence of TEM-1 gene by PCR. out of the 120 klebsiella pneumonia isolates, 13 (10.83 %) isolates were ESBL positive, 5.3 % of which were positive for TEM-1 B-lactamase resistance gene. Considering the increasing rate of the ESBLs producing strains, using the appropriate treatment protocol based on the antibiogram pattern of the strains is highly recommended.