The susceptibility of 10 antimicrobials against P. aeruginosa isolated from complicated UTI during 1992-1995 was determined, and the yearly trend was examinated. The drug tested included 3 cephems (ceftazidime [CAZ], cefpirome [CPR], cefclidin [CFCL]), 1 monobactam (aztreonam [AZT]), 2 carbapenem (imipenem/cilastatin [IPM/CS], biapenem [BIPM]), 2 aminoglycosides (netilmicin [NTL], gentamicin [GM]) and 2 new quinolones (ofloxacin [OFLX], ciprofloxacin [CPFX]). A total number of isolates of which MIC were determined was 77 in 1992/1993 and 70 in 1994/1995. MIC₅₀/MIC₉₀ (pμg/ml) on the isolates were as follows (1992/1993 1994/1995); 3.13/100 12.5/50 in CAZ, 12.5/100 12.5/100 in CPR, 3.13/25 1.56/25 in CFCL, 6.25/50 12.5/100 in AZT, 6.25/25 3.13/25 in IPM/CS, 1.56/6.25 0.78/50 in BIPM, 12.5/100 6.25/100 in NTL, 6.25/50 6.25/100< in GM, 25.100< 25/100< in OFLX, 6.25/100 6.25/100< in CPFX. When the susceptibility of the yearly trend is compared, no significant changes were detected among the drugs tested expect the decrease of susceptibility on CAZ, AZT and increase of it on IPM/CS. From the data obtained, against complicated UTI infected by P.aerugunosa, CFCL, IPM/CS and BIPM are considered to drugs of first choice in the treatment.