The efficacy of two regimens of ciprofloxacin was compared in a randomized study conducted on 69 patients with enteric fever, 52.2% of whom had infection with multidrug-resistant (MDR) strains of Salmonella typhi or S. paratyphi. Patients were randomly assigned to two regimens (10 days versus 14 days) of ciprofloxacin (500 mg twice a day). The mean +/- SD time required for defervescence was similar for both regimens (4.2 +/- 1.9 days in the 10-day group and 4.9 +/- 2.6 days in the 14-day group). A 100% cure was observed in each treatment group and no serious side effects were observed. Relapse occurred in two patients (14-day regimen). Only one patient (14-day regimen) had growth of S. typhi in stool culture at the time of the first follow-up three days after completion of therapy. Follow-up studies on available patients on two, six, and 12 months after completion of therapy revealed that all patients had negative stool cultures for S. typhi and S. paratyphi. This study indicates that ciprofloxacin may be recommended as an initial therapy for enteric fever for adult men and nonpregnant and nonlactating women in areas where MDR strains of S. typhi and S. paratyphi are prevalent, and that 500 mg twice a day of the drug given for 10 days is as effective as 14 days at the same dosage.