Several published studies have reported on the estimated costs associated with overactive bladder (OAB) -a condition characterized by the symptom of urinary urgency, not necessarily accompanied by incontinence, and often associated with urinary frequency and nocturia. Although OAB has been ranked among the 10 most common chronic conditions in the United States, no known published research has rigorously analyzed a key cost component -the number of medical visits associated with this condition. OBJECTIVES: This study was designed to explore US national data sets to recover component estimates of resource use (c.f., office visits, emergency visits, hospitalizations) associated with symptoms of OAB. METHODS: We examined US national databases to estimate the number of annual OAB-associated medical visits among patients at least 18 years of age. Three datasets were used and included the National Ambulatory Medical Care Survey (NAMCS), National Hospital Ambulatory Medical Care Survey (NHAMCS), and the National Hospital Discharge Survey (NHDS). Design based statistical analyses were used to fully account for the complex survey designs. Diagnostic codes identifying patients with OAB symptomatology included ICD-9-CM 788.31, 788.41, and 788.33. RESULTS: During year 2000, there were an estimated 1.4 million (95% CI: 1.1-1.8 million) US ambulatory visits, with symptoms characteristic of OAB, made to nonfederal office-based physicians. Even accounting for ER and outpatient department visits as well as nonfederal short-stay hospital discharges, the estimated number of medical visits with OAB-associated symptoms was less than 1.5 million. CONCLUSIONS: Based on data derived from the NOBLE program, a telephone and postal survey designed to evaluate the prevalence of OAB, there are as many as 34 million adult Americans with OAB. Thus, conservatively assuming one annual medical encounter per patient, as few as 4% of these individuals sought medical treatment during the year 2000. These statistics, therefore, suggest a large unmet medical need.