The efficacy, tolerability and side effects of a 'single-dose' therapy for acute female lower UTIs in general practice with fosfomycin trometamol (3 g) or norfloxacin (800 mg) were compared in a randomized double-blind study. 89 patients were included in the trial; however, 36 (40.4%) did not present significant bacteriuria and were assessed mainly for tolerability. Of the 53, 28 patients in the fosfomycin trometamol group and 25 patients in the norfloxacin group, 21 (75%) had no bacteriuria at immediate follow-up after treatment with fosfomycin trometamol and 20 (84%) with norfloxacin. The tolerability of both drugs in single dose was absolute.