Susceptibilities of Citrobacter spp., Enterobacter spp., Escherichia coli, Klebsiella spp., Proteus mirabilis, Pseudomonas aeruginosa, Serratia spp. isolated from patients with urinary tract infections (UTIs) in 10 hospitals during June 1989 to May 1990 to various antimicrobial agents were compared with those in the same period of previous years according to a classification, uncomplicated UTIs, complicated UTIs without indwelling catheter, and complicated UTIs with indwelling catheter. As for Citrobacter spp., P. mirabilis and Serratia spp., which were detected very few in 1989, their susceptibilities were not observed an obvious change. As for Enterobacter spp., the susceptible strains to flomoxef, cefixime, cefuzonam and ceftazidime increased in complicated UTIs with indwelling catheter. The susceptibilities of E. coli to penicillins increased slightly in complicated UTIs with indwelling catheter. Against Klebsiella spp., a good activity of minocycline or cephems was found. The susceptibilities of P. aeruginosa to ciprofloxacin and new quinolones increased in uncomplicated UTIs. These data should be considered in clinical treatment of various urinary tract infections.