Overactive bladder (OAB) is a condition with bothersome urinary symptoms including an increased need to urinate (urgency), increased frequency of urination, getting up at night to urinate, or involuntary urination. Patients should have a realistic goal for treatment and an understanding of the risks versus benefits of particular treatments. The objective of the study was to analyse the efficacy and safety of Darifenacin and Mirabegron once daily in patients with Overactive Bladder (OAB) treated for 1month. A prospective observational study of 71 which all are newly diagnosed with OAB. Efficacy end points were changed from baseline in OABSS total score. Patients were instructed to complete the OABSS sheet before therapy, after 48 hrs, after 1 week and after 1 month of therapy. On comparing both drugs, Mirabegron and Darifenacin, we found both drugs showing almost similar side effects constipation [29.2%, 76.6%], blurred vision [26.8%, 66.6%], dry mouth [24.3%, 83.3%], headache [17%, 30%] and hypertension [48.7%, 10%]. The data indicate that mirabegron has a favourable efficacy and tolerability balance, and represents an alternative treatment option to Darifenacin for patients with OAB