Enoxacin (ENX) was administered to 69 patients with complicated urinary tract infections (UTI). Clinical efficacy and safety were evaluated by the criteria proposed by the UTI Committee, Japan. The overall clinical efficacy was excellent in 60.9%, moderate in 10.1% and poor in 29% of the patients. Of the 76 strains isolated from the patients 61 strains (80.3%) were eradicated. Subjective side effect was observed in one patient who complained of slight nausea. No drug-related aggravation in the laboratory test was observed. These results showed that ENX was effective and safety for the treatment of complicated urinary tract infection.