Background/Aim: In clinical practice, constipation is one of the most frequent adverse events caused by drugs for overactive bladder (OAB). The occurrence of constipation greatly deteriorates the patient’s quality of life. The aim of the study was to evaluate and compare the effects of three commonly used β3 agonists and anticholinergic drugs on the defecation status in patients with OAB. Patients and Methods: We retrospectively reviewed the defecation status in patients who received mirabegron, solifenacin, or fesoterodine for OAB. We evaluated changes in the (a) urological parameters using the OAB symptom score (OABSS) and (b) defecation status using the Bristol Stool Form Scale (BSFS) and constipation scoring system (CSS) following 12 weeks of drug administration. Results: We analyzed data from 165 patients (mirabegron=56, fesoterodine=52, and solifenacin=57). The solifenacin group showed a significant decrease in BSFS (from 3.2±1.0 at baseline to 2.3±1.2 post-treatment) and an increase in hardened stools (p