Currently, antimuscarinics are the most commonly used drugs for the treatment of overactive bladder (OAB). Improving quality of life and treatment satisfaction are key factors for adherence to therapy. Mirabegron, the first drug in the class of b3-adrenergic receptor agonists, is used as an alternative to antimuscarinic drugs in the treatment of OAB and it has proved efficacy and excellent safety profile. Observational studies can provide data on the efficiency of therapy in routine clinical practice, and real-life data indicate that the duration of treatment with mirabegron may be longer compared with that of antimuscarinic drugs. A prospective study (BELIEVE) has been the largest European study which evaluated quality of life, treatment satisfaction and adherence to therapy in patients with OAB who were prescribed mirabegron in routine clinical practice. The BELIEVE study has been approved by regulatory authorities in all participating countries based on local requirements. The primary end point was to evaluate the change in quality of life compared to baseline based on the OAB questionnaire. Secondary end points included evaluating treatment duration, patient satisfaction, use of health resources, and side effects. Subsequent observation was provided for 12 months with follow-up visits after 2-4 and 10-12 months of therapy. A total of 862 862 patients from 8 European countries were included in the study. 73.7% of patients were women, and the average age was 61.2 years; 47.7% of patients were older than 65 years. At the beginning of the study, 41.3% of patients preferred other types of treatment, 42.2% were treatment-nave, 10.1% dropped out of the study, 6.4% received combination therapy. Storage symptoms and general quality of life improved from baseline to 2-4 and 10-12 months. There was a marked improvement in continence rate, increasing from 34.9% at the beginning to 43.7% after 10-12 months, and the use of pads decreased. Adherence to therapy was at a high level: 53.8% of patients continued taking mirabegron after 10-12 months. In general, no unexpected adverse events were observed, and they were consistent with the described safety profile of mirabegron. Patients receiving mirabegron reported a significant improvement in their quality of life and health status, while the level of adherence for the drug was 53.8% for 12 months. No unexpected safety problems were found, and side effects were consistent with previously described safety profile.