Bladder overactivity (OAB) is a common disease with a socioeconomic impact comparable to diabetes mellitus. As life expectancy rises in industrialized countries the importance of OAB will further increase. The International Continence Society (ICS) recently reported a modified terminology for lower urinary tract function and established the symptom-based term OAB. The etiology of OAB comprises neurogenic and non-neurogenic detrusor hyperactivity as well as detrusor hypersensitivity. Neurogenic detrusor hyperactivity may be caused by insufficient cortical inhibition, degenerative neuropathies, and spinal cord lesions, whereas bladder aging, bladder outlet obstruction, and chronic bladder irritation (UTI, stones, tumors) are possible causes for non-neurogenic detrusor hyperactivity. Since most epidemiologic surveys focus on urge incontinence without considering urgency frequency without incontinence, epidemiologic data concerning OAB are rare. Two recently published multinational prevalence studies from Europe and Asia show different prevalence values [Europe: 15.6% (men), 17.4% (women); Asia: 53.1%(women)], which may be due to methodological differences. Both studies report an increase of OAB prevalence corresponding with age. The cumulative incidence of OAB is rising faster in aging males than in aging females. Two-thirds of the European and one-fourth of the Asian individuals affected by OAB complained about impaired quality of life, but only 60% of the European and 21% of the Asian sufferers have talked to a doctor or sought treatment. One out of four patients visiting their health care professional for OAB symptoms is currently under medication. To avoid high treatment costs and side effects, pharmacotherapy (e.g., antimuscarinics) should only be given after detailed diagnostic evaluation.