In a coordinated, double-blind multi-centre trial, adults with symptoms of acute pyelonephritis were randomly assigned to receive a two-week course of oral treatment with either 400 mg norfloxacin twice daily or 1 g cefadroxil twice daily. Of 197 patients enrolled in the study, 140 could be evaluated for drug efficacy and 193 for drug safety. Norfloxacin gave a significantly higher bacteriological cure rate than cefadroxil, both at 3 to 10 days (98 % versus 65 %; p<0.0001; 95="" %="" confidence="" interval="" (ci)="" for="" difference="" in="" proportions="" 21–46="" %)="" and="" up="" to="" eight="" weeks="" (87="" %="" versus="" 48="" %;=""><0.0001; 95="" %="" ci="" 25–54="" %)="" after="" cessation="" of="" treatment.="" the="" differences="" between="" the="" two="" regimens="" were="" most="" pronounced="" in="" men="" and="" in="" patients="" with="" complicating="" factors="" such="" as="" diabetes="" mellitus="" and="" urinary="" tract="" abnormalities.="" the="" clinical="" response="" during="" treatment="" did="" not="" differ="" between="" the="" two="" groups,="" but="" symptomatic="" recurrences="" at="" follow-up="" were="" more="" common="" in="" the="" cefadroxil="" group="" (28="" %="" versus="" 3="" %;=""><0.0001; 95="" %="" ci="" 14–36="" %).="" adverse="" events="" were="" more="" often="" reported="" by="" patients="" receiving="" cefadroxil="" (39="" %="" versus="" 22="" %;="" p="0.011;" 95="" %="" ci="" 4–30="" %)="" and="" consisted="" mainly="" of="" gastrointestinal="" disturbances="" and="" vulvo-vaginitis.="" in="" terms="" of="" bacteriological="" and="" clinical="" efficacy="" and="" safety,="" a="" two-week="" course="" of="" norfloxacin="" was="" superior="" to="" a="" two-week="" course="" of="" cefadroxil="" for="" oral="" treatment="" of="" community-acquired="" acute="">