The efficacy and safety of lomefloxacin 400 mg daily in the treatment of complicated urinary tract infections were confirmed in a randomized multicenter study that enrolled 294 patients from 16 centers in Italy. A total of 155 patients were treated with 400 mg lomefloxacin once daily for 15 days while a total of 139 patients received 500 mg of ciprofloxacin twice daily for 15 days. Eradication of the initial pathogen was observed in 87% of patients treated with lomefloxacin and in 81% of ciprofloxacin-treated patients while clinical success was achieved in 85% of lomefloxacin-treated patients and in 76% of patients treated with ciprofloxacin. The differences in outcome between the two treatment groups were not statistically significant (chi 2 = ns). Both drug regimens were well tolerated and no patients discontinued treatment due to adverse events. In conclusion, once-daily lomefloxacin was as effective as twice-daily ciprofloxacin in the treatment of complicated urinary tract infections.