The clinical efficacy and safety of intravenous micronomicin (MCR) therapy were evaluated in cases with complicated urinary tract infections. MCR was administered to 13 patients by intravenous drip infusion over a period of 1 hour, in a dose of 120 mg twice daily for 5 consecutive days. Therapeutic results were evaluated by the criteria proposed by UTI committee and the judgement of the doctor in charge and the overall clinical efficacy rate was 69% (9/13) and 85% (11/13), respectively. Among 18 strains isolated before treatment, 15 strains were eradicated and bacteriological efficacy rate was 83%. No side effects including nephrotoxicity and ototoxicity associated with the treatment were noted, except for 1 case with transient elevation of A1-P.