Objective: The overactive bladder syndrome (OAB) involves frequency, nocturia, and urgency with or without urgency incontinence. This study aims to evaluate the effects of a fesoterodine fixed-dosing (4 mg) regimen on OAB symptoms and sexual function in OAB subjects using standardized questionnaires. Methods: This study included 40 patients with OAB in a severance hospital from 2010 to 2012. OAB patients were treated with fixed-dose fesoterodine (4 mg, daily) for 4 months. We assessed to fesoterodine efficacy by Overactive Bladder Symptom Score (OABSS), Overactive Bladder Questionnaire (OAB q), Female Sexual Function Index (FSFI), and Pelvic Organ Prolapse/Urinary Incontinence Sexual Function questionnaire-12 (PISQ-12) were performed from baseline to 16 weeks. Results: The main outcomes, i.e., the OABSS, OAB q, FSFI, and PISQ-12 scores, also changed from baseline to 4 months after treatment in the OAB group. The mean OABSS and OAB q scores changed significantly (p<0.001). Urgency and urinary incontinence, as measured by the OABSS, also decreased after anticholinergic treatment (p <0.001, for both comparisons). In addition, the OAB q scores, including Symptom Bother and the four HRQL subscales, improved after anticholinergic treatment (p<0.001). Statistical increases in the total PISQ-12 and FSFI scores were observed. The results of the FSFI indicated that the desire (from 2.40±1.02 to 2.53±1.09) and satisfaction domains(from 2.87±1.62 to 3.04±1.72) were improved (P<0.05). The scores for two questions (Do you climax when having sexual intercourse with your partner? and Do you feel sexually excited when having sexual activity with your partner?) were increased in the PISQ-12 ( P<0.05). Conclusion: It makes improvement of OAB symptoms, HRQL and improvements of sexual functions were seen in OAB patients 4-mg fesoterodine treatment. Despite of evidence guiding long-term effect on their sexual activity, this provides evidence for a more progressive approach.