Overactive bladder (OAB) describes complex symptoms, comprising of urinary urgency, with or without urinary incontinence, often with increased daytime frequency and nocturia in the absence of infection or other obvious etiology. OAB is highly prevalent and affects physical and mental health, activities of daily life and the quality of life of millions of adults. The pathophysiology of OAB and detrusor overactivity is still not completely known, but is most probably multifactorial.The epidemiology and pathophysiology of OAB is reviewed. A literature search using PubMed from 2000 to 2010 was undertaken for this review with pertinent older papers referenced as needed to gain a clearer understanding of the epidemiology of OAB and related bladder pathophysiology, which it is hoped will lead to more effective and better-tolerated treatments for OAB.With recent advances in our understanding of the basic science of OAB, it is becoming clear that the control of bladder function is far more complex than previously believed. Recent research has highlighted several potential targets for the treatment of OAB, particularly within the mechanosensory pathways.