Overactive bladder syndrome (OAB), with or without urge incontinence, is characterized by urinary urgency, frequency and nocturia. Thus, patients with OAB could be considered to have a reduced quality of life. Patients with overactive bladder syndrome have a higher risk of falling and fracture due to nocturia. OAB affects around 17 % of female population. At present, muscarinic receptor antagonists are the ﬁrst-line pharmacotherapeutic agents for OAB. However, discontinuation of the treatment often results in symptom relapse. Until now, optimal duration of the treatment and durability of the efﬁcacy have not been determined. We plan to use urodynamic studies outcome to evaluate therapeutic effect, with the change of urinary nerve growth factor level. This study is a randomized prospective study, comparing female OAB patient after 3 months and 6 months of antimuscarinic treatment.