Eighty-five girls, ages 3-16, with a past history of recurrent urinary tract infections were treated for 10 days with either trimethoprim/sulfamethoxazole, ampicillin or cephalexin. Patients with normal roentgenograms as well as those with reflux and cortical scarring were included. In the 12 weeks following completion of treatment, a significantly lower recurrence rate was noted in children who received trimethoprim/sulfamethoxazole. There was no difference in the recurrence rate whether or not radiographic abnormalities were present. No serious side effects were noted with any drug regimen.