The long term objectives are to: . reduce the human and health care costs of recurrent UTIs . reduce the need for antibiotic therapy for recurrent urinary tract infections in adult women . reduce the number of physician visits for UTIs The specific aims of this project are to determine: 1. the minimum dose of cranberry product necessary to achieve 30% prophylaxis of urinary tract infections in women with recurrent urinary tract infections 2. whether degree of prophylaxis is related to dose of cranberry product (dose-response curve) 3. whether proanthocyanidin concentration in the urine correlates with prophylaxis 4. temporal relationship between consumption of cranberry products and urinary proanthocyanidin levels 5. whether cranberry product is effective against all, or only specific strains of E coli 6. whether there is a long-term benefit to a year of therapy 7. whether there are adverse effects associated with prolonged or high levels of cranberry consumption This study is a dose-response trial of cranberry tablets/capsules, comparing the efficacy of 5 dose levels: placebo, very low dose, low dose, medium dose and high dose. Participants, 250 adult women who have had at least 2 single-organism urinary tract infections in the preceding 12 month period but who are currently free of urinary tract infection, will be randomly assigned to one of the arms of the study. Exclusion criteria are: active urinary stone disease, allergy to cranberries, diabetes, and pregnancy. All participants will have a complete history, physical examination, urinalysis, urine culture, and renal ultrasound prior to enrolment in the study. The primary outcome measure will be number of single-organism urinary tract infections in a 12-month period. Secondary outcomes will be proanthocyanidin concentration in the urine, oxalate concentration in a 24 hour urine (6 women per group), temporal relationship between intake of cranberry product and urinary proanthocyanidin levels (6 women per group), and cost-benefit analysis.