In a multicenter, prospective, double-blind, double-dummy randomized study conducted in Israel and Germany, the efficacy and safety of ciprofloxacin 250 mg b.i.d. versus ofloxacin 200 mg b.i.d. was compared in the treatment of women with complicated lower urinary tract infection. A total of 465 women were enrolled in the study, 427 of whom were included in the intent-to-treat analysis. Two hundred fourteen received ciprofloxacin 250 mg b.i.d. and 213 received ofloxacin 200 mg b.i.d. Both regimens were administered for 7 days. The primary efficacy parameter was the microbiologic result obtained 5-9 days after cessation of therapy; secondary efficacy parameters were urine cultures obtained 28-42 days after the end of therapy and clinical outcome 5-9 days and 28-42 days post-therapy. There were no relevant differences in the primary efficacy parameter or in any secondary efficacy parameter between the average response rate of patients who received ciprofloxacin and that of patients who received ofloxacin: 90.1% of the ciprofloxacin group and 87.2% of the ofloxacin group had sterile urine 5-9 days after the end of therapy; 77.1% and 76.1% had sterile cultures, respectively. Clinical cure was achieved in 97.2% of both groups 5-9 days after cessation of therapy and a month later in 87.7% and 87.3%, respectively. Adverse events were mild and similar in both groups. In conclusion, for the primary efficacy parameter as well as for all secondary efficacy parameters, ciprofloxacin 250 mg b.i.d. is at least as effective as ofloxacin 200 mg b.i.d. in women with complicated lower urinary tract infection.