In this study, cefditoren pivoxil (ME 1207, CDTR-PI), a new oral cephem antibiotic, was given to 72 patients with non-catheterized complicated urinary tract infections (UTI) to evaluate clinical efficacy and safety, and also to investigate the rate of recurrence after completion of treatment. Daily dose of CDTR-PI was 100 mg t.i.d., and CDTR-PI was administered for 14 days. According to the criteria proposed by the Japanese UTI Committee, clinical efficacy of CDTR-PI was evaluated at day 7 and day 14. The rate of recurrence was assessed by bacterial count in urine as the marker. The following results were obtained. 1. Overall clinical efficacy rates were 68.4% on day 7 and 81.6% on day 14. The efficacy rate at day 14 was higher than the rate at day 7. 2. Bacteriologically, eradication rates were 75.5% at day 7 and 79.6% at day 14. 3. As to side effects, abdominal discomfort was observed in 1 case and its incidence was 1.6%. Incidence of abnormalities of laboratory findings was 10.4%, and these abnormalities were slight and transient. 4. Thirty-one patients were assessable to the recurrence of infections, 60% of them were judged as "cured" at 1-2 weeks and 3-7 weeks after completion of treatment. In this study, "relapsed", reappearance of causative organisms, was observed much more frequently than "reinfection". These results suggest that sufficient clinical efficacy and safety of CDTR-PI in non-catheterized complicated UTI were effected by 14 days treatment.