Objective To evaluate the combined inhibitory effect of cefepime (FEP) and meropenem (MEM),FEP and ciprofloxacin (CIP) respectively on clinically isolated multidrug resistant pseudomonas aeruginosa (MDRPA) strains in vitro. Methods Combined inhibitory effect of FEP and MEM, FEP and CIP in vitro was assayed by detecting the minimum inhibitory concentration (MIC) and calculating the fractional inhibitory concentration index for 58 MDRPA strains with the agar dilution method. Results Combined FEP and MEM showed 32.8% synergic effect, 46.6% additive effect, 20.6% unrelated effect, no antagonistic effect on MDRPA strains. Combined FEP and CIP displayed 20.7% synergic effect, 51.7% additive effect, 27.6% unrelated effect and no antagonistic effect on MDRPA strains. The MIC₅₀ of these drugs was significantly lower when they were used in combination, with their concentration-accumulative inhibition curves shifted to the left. Conclusion FEP combined with either MEM or CIP, compared with respective use, showes an elevated drug sensitivity for MDRPA strains in vitro.