Despite considerable controversy about their effects, cranberries in various forms have been used widely for several decades to prevent as well as treat urinary tract infections (UTIs). The purpose of this article is to present a review of research-based information regarding the ability of cranberries to prevent UTIs in adults at risk for UTIs. Current evidence suggests that cranberries decrease bacterial adherence to uroepithelial cells and thus decrease the incidence of UTIs without adverse effects in most individuals. Thus clinicians may safely advise patients that cranberries are helpful in preventing UTIs. Cranberries may be a viable adjunct to antibiotics for patients with repeated UTIs.