Background: Extended spectrum β-lactamases (ESBLs) have emerged as a major threat worldwide, with limited treatment options available. Objectives: The present study aimed to estimate the prevalence, possible types of ESBL genes and antibiotic resistant patterns of ESBLproducing Escherichia coli (E. coli) and Klebsiella pneumoniae (K. pneumoniae). Materials and Methods: A total of 199 clinical isolates of E. coli and K. pneumoniae, collected between October 2010 to March 2012, at three University Hospitals in Aleppo city center, in north Syria, were examined phenotypically and genotypically for ESBL production. Results: The ESBLs were found in (62.89%) of E. coli and (67.5%) of K. pneumoniae isolates. The majority of the typeable isolates harbored two or more ESBL genes (73%). Overall, bla CTX-M-1 was the commonest genotype (81.74%). Resistances of ESBL isolates to other antibiotics were measured: tremithoprim/sulfamethoxazole (72%), nalidixic acid (72%), tetracycline (66%), gentamicin (54%) and ciprofloxacin (53%). Conclusions: Our study showed high ESBL incidence, with CTX-M genotype as the emerging strain in our hospitals. High co-resistance to other non-β-lactam antibiotics is a major challenge for the management of ESBL infections.