OBJECTIVES: The Vanderbilt Evidence-based Practice Center systematically reviewed evidence on treatment of overactive bladder (OAB), urge urinary incontinence, and related symptoms. We focused on prevalence and incidence, treatment outcomes, comparisons of treatments, modifiers of outcomes, and costs. DATA: We searched PubMed, MEDLINE, EMBASE, and CINAHL. REVIEW METHODS: We included studies published in English from January 1966 to October 2008. We excluded studies with fewer than 50 participants, fewer than 75 percent women, or lack of relevance to OAB. Of 232 included publications, 20 were good quality, 145 were fair, and 67 poor. We calculated weighted averages of outcome effects and conducted a mixed-effects meta-analysis to investigate outcomes of pharmacologic treatments across studies. RESULTS: OAB affects more than 10 to 15 percent of adult women, with 5 to 10 percent experiencing urge urinary incontinence (UUI) monthly or more often. Six available medications are effective in short term studies: estimates from meta-analysis models suggest extended release forms (taken once a day) reduce UUI by 1.78 (95 percent confidence interval (CI): 1.61, 1.94) episodes per day, and voids by 2.24 (95 percent CI: 2.03, 2.46) per day. Immediate release forms (taken twice or more a day) reduce UUI by 1.46 (95 percent CI: 1.28, 1.64), and voids by 2.17 (95 percent CI: 1.81, 2.54). As context, placebo reduces UUI episodes by 1.08 (95 percent CI: 0.86, 1.30), and voids by 1.48 (95 percent CI: 1.19, 1.71) per day. No one drug was definitively superior to others, including comparison of newer more selective agents to older antimuscarinics. Current evidence is insufficient to guide choice of other therapies including sacral neuromodulation, instillation of oxybutynin, and injections of botulinum toxin. Acupuncture was the sole complementary and alternative medicine treatment, among reflexology and hypnosis, with early evidence of benefit. The strength of the evidence is insufficient to fully inform choice of these treatments. Select behavioral interventions were associated with symptom improvements comparable to medications. Limited evidence suggests no clear benefit from adding behavioral interventions at the time of initiation of pharmacologic treatment. CONCLUSIONS: OAB and associated symptoms are common. Treatment effects are modest. Quality of life and treatment satisfaction measures suggest such improvements can be important to women. The amount of high quality literature available is meager for helping guide women's choices. Gaps include weak or absent data about long-term followup, poorly characterized and potentially concerning harms, information about best choices to minimize side effects, and study of how combinations of approaches may best be used. This is problematic since the condition is chronic and a single treatment modality is unlikely to fully resolve symptoms for most women.