Objective To investigate the resistance of clinical isolates of P.aeruginosa in China during 2005.Methods Clinical isolates of P.aeruginosa from 7 teaching hospitals in China were collected and antimicrobial susceptibility were tested by Kirby-Bauer method.Results A total of 2 323 clinical isolates of P.aeruginosa were collected.The resistance rates of P.aeruginosa to antimicrobial agents from low to high were amikacin(22.5%),cefoperazone-sulbactam(22.8%),cefepime(27.6%),ceftazidime(28.9%),imipenem(31.3%),ciprofloxacin(31.7%),meropenem(33.7%),piperacillin-tazobactam(34.4%),aztreonam(36.8%),piperacillin(44.2%),ticarcillin-clavulanic acid(50.9%).Multi-drug resistant(MDR)and pan-drug resistant(PDR)strains accounted for 8.4% and 4.2%,respectively.Some(36.7%-53.4%)of the strains resistant to other antimicrobial agents were still susceptible to amikacin.Therefore,combination therapy of ?-lactams plus an aminoglycoside is usually indicated for serious infections caused by P.aeruginosa.By 'interpretative reading' of the susceptibility pattern of 'predictive drugs',we can predict the underlying resistance mechanisms.Conclusions The surveillance data indicate that the resistance of P.aeruginosa in China is relatively serious and its resistance mechanisms are very complicated.Close attention should be paid to this problem by physicians and clinical laboratory.