BACKGROUND Knowledge of the anti-microbial susceptibility pattern of common pathogens in a given area helps to inform the choice of empirical antibiotic therapy. The aim of this study was to determine the existence and to describe the characteristics of extended spectrum beta-lactamase (ESBLs) in a pediatric hospital in Mansoura University, Egypt, to aid in the choice of empirical antibiotic therapy. METHOD Between January 2005 and December 2006, blood samples were collected from children suspected to have nosocomial infections in a pediatric hospital in Mansoura. The gram negative isolates were identified, tested for antimicrobial susceptibility and analyzed for presence of ESBL. RESULTS A total of 1,600 children with suspected septicemia were studied. Gram negative septicemia was identified in 816 cases (45%). The commonest isolated gram negative bacilli was Klebsiella species (38.2%) followed by Enterobacter species (32.4), Serratia species (16.2%) and Burkholderia cepacia (10.3%). The highest susceptibility was for imipenem (74.3%) followed by gentamicin (70.8%), cefoperazone (64.5%) and cefotaxime (63.2%). The highest resistant rate was for cefazolin and ampicillin/sulbactam (75.5% for each), followed by cefuroxime 70.3% and ceftriaxone (63.5%). The ESBL was found in 44.5% for cefotaxime and 50% for ceftazidime by double discs method. CONCLUSION This study highlights the emergence of antibiotic resistant gram negative bacilli in a pediatric hospital with special emphasis on extended beta-lactamase resistant strains. Our results show that the most appropriate antibiotics to be used for empirical therapy are amikacin and gentamicin.