Two separate outbreaks of Pseudomonas aeruginosa urinary tract infections (UTIs) were associated with cystoscopy or transurethral prostate resection. The first outbreak was identified after routine bacteremia surveillance demonstrated four cases of P aeruginosa septicemia in a three-month period. A six-month retrospective review of the microbiology records identified 14 cases of P aeruginosa UTI associated with urologic surgery instrumentation. The outbreak terminated after the implementation of two major control measures: (1) replacement of hexachlorophene solution with an iodophor solution for preparing patients and cleaning instruments before disinfection, and (2) weekly gas sterilization of cystoscopy instruments. The second outbreak, consisting of 11 cases of P aeruginosa UTI after transurethral resection of the prostate gland, occurred in a 187-bed community hospital. All available patient isolates were serotype 011, and culture of a rubber adaptor attached to the resectoscope also yielded growth of that serotype. The outbreak promptly terminated when the rubber adaptor was sterilized between cases.