Ticarcillin-clavulanic acid (Claventin) and amikacin were administered in an open study to prevent and treat nosocomial urinary tract infections, to 59 patients after major urological surgery. Postoperative course was event-free in 44 cases. 10 patients presented asymptomatic urinary tract infections due to gram negative bacilli, that did not require any change in antimicrobial therapy. 5 patients experienced symptomatic nosocomial infections, whose one was associated with a methicillin-Resistant Staphylococcus aureus septicemia that was treated by vancomycin. The urinary tract infections were polymicrobial in only 3 cases. The tolerance was quite satisfactory, and the protocol was effective in about 92% of cases. The combination of ticarcillin-clavulanic acid-amikacin is valuable and can be used as first step therapy to preserve the ecology of the patients.