A double-blind, randomized controlled study to evaluate the efficacy and safety of a single dose of 500 mg of ciprofloxacin versus 3 days 400 mg twice-daily of norfloxacin in uncomplicated urinary tract infection in women was designed. Patients underwent four visits: baseline, and at 3, 7 and 28 days. The main efficacy variables were clinical and microbiological outcome at day 7. Analyses on both valid patients and intention-to-treat populations were performed. Two hundred and twenty-six patients (114 receiving ciprofloxacin and 112 receiving norfloxacin) were considered valid for efficacy evaluation. Bacteriologic cure was 91.2% in the ciprofloxacin group and 91.9% in the norfloxacin group. Clinical resolution was 91.2 and 93.8%, respectively. Both treatments were equally efficacious (P = 0.016).