OBJECTIVE: To describe the profile of the overactive bladder (OAB) patient on treatment with flexible-dose antimuscarinic treatment in daily clinical practice. METHODS: This was an observational, retrospective and multicenter study, carried out at 88 public and private hospitals. Adult patients diagnosed with OAB who initiated flexible-dose antimuscarinic treatment. Type of antimuscarinic, dose, concomitant treatments, treatment benefit and treatment adherence were recorded. RESULTS: This was a pluripathological (83.5%) and polymedicated (73.4%) population, comprised of 846 patients, mostly women (74.5%) with a mean (SD) age of 61.3 (12.1) years and more than one year of OAB evolution. Main initially prescribed antimuscarinics were fesoterodine (66.5%) and solifenacine (30.0%). Overall, 68.2% of the patients started treatment with the low dosage; at the follow-up visit 47.0% changed the dosage (84.2% increased the dosage, 15.8% decreased the dosage). Patients who changed the dosage showed a significantly greater morbidity, worse OAB symptoms, greater health resources use, and worse adherence to treatment compared with those that maintained the high dosage all the time. CONCLUSION: No differences were found regarding the demographic or clinical characteristics that allow us to identify which patients should receive the different options of available dose of antimuscarinic drugs, although greater benefits seem to be achieved with the use of the highest or the lowest dose from the outset than with the change of dose.