The diagnosis of OAB depends largely on patient self-described symptoms of frequency, nocturia, and urgency. Many patients avoid discussing the issue with their physicians and delay in seeking care. When taking a history, age, onset, description, nocturia, prior therapy, history of neurological disorders and patients’ expectations are the main topics to discuss with the doctor. In addition a simple physical exam of the abdomen and pelvic area is necessary to complete the initial evaluation. A voiding diary is very important and provides useful information. The volume of each void is key. The diary also allows for baseline and comparative assessment of a treatment. The night and first morning voids are most likely to demonstrate the bladder’s ability to store urine. Special questionnaires are also very useful to measure the severity and bother from OAB and these can also be used to evaluate efficacy and progress from a given treatment option.