["Pathophysiology and treatment of the overactive bladder"]. Yokoyama Osamu Hinyokika kiyo. Acta urologica Japonica The International Continence Society (ICS) recently derived a consensus symptomatic definition of overactive bladder (OAB) as urinary urgency, with or without urge incontinence, usually with frequency and nocturia. These symptom combinations are suggestive of urodynamically demonstrable detrusor overactivity. The etiology of OAB falls into two broad categories: neurogenic and nonneurogenic. It is not easy to confirm the etiology of OAB in patients with bladder outlet obstruction and neurological disease. This debate has attempted to examine the pathophysiology of OAB and to determine the optimal treatment strategy in a patient with two diseases possibly causing OAB. A 75-year-old man visited our hospital due to symptoms of OAB (urgency, nocturia, and urge incontinence) occurring after cerebrovascular accidents. Urge incontinence worsened concomitantly with the appearance of turbid urine. Urinary tract infection was accompanied by 84 ml of post-void residual. The prostate volume and PSA value were 28 ml and 1.2 ng/ml, respectively. The total International Prostate Symptom Score (IPSS) and Quality of Life (QOL) Index were 23 and 5, respectively. IPSS for storage symptoms was higher than that for obstructive symptoms. The maximum flow rate, measured after treatment for UTI, was 9.4 ml/s. Two debaters discuss the treament modality, TURP, or pharmacotherapy.