OBJECTIVE To approach the constituent ratio and drug-resistance of Gram-negative bacilli(GNB) in nosocomial infections and provide the scientific evidence for the clinical treatment of infectious diseases.METHODS Totally 376 GNB strains isolated from our hospital were cultured and identified according to the National Clinical Laboratory Operation Rules.The antibiotic susceptibility test was performed by K-B method and the constituent ratio of GNB was analyzed statistically.RESULTS The pathogens with strains having higher isolating rate were Pseudomonas aeruginosa(21.5%),Klebsiella pneumoniae(17.6%),Acinetobacter baumannii(14.4%),Escherichia coli(10.9%),and Stenotrophomonas maltophilia(5.9%).The drug sensitivity tests in vitro showed that these strains were multiresistant.Except for natural drug-resistant S.maltophilia,16.0% of P.aeruginosa and 24.1% of A.baumannii were resistant to imipenem.The average detection rate of the extended spectrum ?-lactamase(ELBLs) producers was 40.2%.CONCLUSIONS The resistance status of GNB is very serious.We must strengthen monitoring and controlling of drug resistance.