Overactive bladder is a symptom syndrome with urgency, frequency and, in many cases, nocturia. Urge incontinence is not present in all. There is no direct correlation with detrusor overactivity, an objective finding during urodynamic testing where involuntary contractions can be noticed. In the pathophysiology, much more attention has been given to the afferent/sensory arm of the micturition reflex in the last decade. Anatomical and infectious causes have to be diagnosed or ruled out. Diagnosis of overactive bladder is made mostly by history-taking, but other tests can be necessary in specific patients. Treatment consists of behavioral measures, a good explanation of the condition, training, and pelvic floor physiotherapy. Drugs are often used. Until recently, antimuscarinic drugs have been the mainstay of pharmacological therapy. Fesoterodine is a newer antimuscarinic agent which is more pharmacodynamically stable then tolterodine. Fesoterodine has been extensively researched using different dosages and compared with placebo and tolterodine, in different age groups, and under different conditions. Fesoterodine is superior to placebo and to tolterodine in the short term and long term. Its safety is very acceptable.