Objective To analyze the current drug resistance and risk factors of hospital acquired pneumonia( HAP) due to extended spectrumβ-lactamase ( ESBLs) producing Escherichia coli and Klebsiella pneumoniae, and to estimate the prevalence trend of ESBLs producing strains. Methods FromApril 2007 to January 2008, 140 patients of Xinhua Hospital with HAP due to E. coli and K. pnermoniae were enrolled.Among them, 88 patients were with ESBLs producing strains and 52 patients were with non-ESBLs producing strains. Risk factors were analyzed by comparing between these patients. The rate of drug resistance was determined by antibiotic sensitive test. Fifty-three ESBLs producing strains were genotyped by random amplified polymorphic DNA ( RAPD) . Results The rate of drug resistance of ESBLs producing strains washigher than that of non-ESBLs producing strains. ICU stay, use of third- and forth-generation cehpalosporin were found to be the independent risk factors by multivariate analysis with logistic regression. By RAPD, 37 ESBLs producing E. coli strains were divided into 27 types and 16 ESBLs producing K. pneumoniae strains were divided into 13 types. Conclusions ICU stay, use of third-generation and forth-generation cehpalosporin remain as major risk factors in the HAP due to ESBLs producing E. coli and K. pneumoniae.RAPD is an economic, quick and credible method for epidemic analysis