In 2002, the International Continence Society (ICS) derived a consensus symptomatic definition of overactive bladder (OAB) as urinary urgency, with or without urge incontinence usually with urinary frequency and nocturia, in the absence of pathologic or metabolic factors that would explain these symptoms. OAB is a highly prevalent disorder that increases with age in both sexes and that has a profound impact on quality of life. Although the prevalence of OAB in men and women is similar in Japan, help-seeking in women has been reported to be lower than that in men. One reason is most women with OAB consider it not a serious disease, and another reason is they hesitate to consult a doctor, especially a urologist, because they feel ashamed. On the other hand, the pathophysiology of OAB remains poorly understand. We have demonstrated that Kit-positive interstitial cells in the suburothelial layer and smooth muscle layer played an important role in the mechanism for maintaining bladder function and pathophysiology of OAB. In addition, we showed the effects of Glivec, a c-Kit tyrosine kinase inhibitor, reduced spontaneous action potential in detrusor smooth muscle. Glivec may prove useful for the treatment of OAB in the future.