This study investigated the effectiveness and tolerability of brivaracetam (BRV) monotherapy in a large series of patients with epilepsy. This was a multicenter, retrospective, observational, non-interventional study in 24 hospitals across Spain. Patients aged ≥18 years who started on BRV monotherapy, either as first-line or following conversion, at least 1 year before database closure were included. Patients were evaluated at baseline and at 3, 6 and 12 months after initiation of BRV monotherapy, in accordance with usual clinical practice at these centers. Data were collected retrospectively from patients' individual charts by participating physicians. The primary effectiveness and safety endpoints were the percentage of seizure-free patients 1 year after initiation of BRV monotherapy and the proportion of patients reporting adverse events (AEs) over the complete follow-up period. Retention rates and subpopulation analysis (levetiracetam switchers, elderly and different etiologies) were also investigated. A total of 276 patients were included (48 with BRV as first-line monotherapy and 228 who converted to BRV monotherapy). The overall retention rate in monotherapy at 12 months was 89.9% (87.5% for first-line monotherapy group; 90.4% for conversion-to-monotherapy group). Seizure-freedom rates at 12 months were 77.8% (75% for first-line monotherapy group; 78.4% for conversion-to-monotherapy group). AEs occurred in 39.5% of patients at 12 months (35.4% for first-line monotherapy group; 40.4% for conversion-to-monotherapy group). Most AEs were mild-to-moderate. The most frequent AEs were irritability (12.3%) and dizziness (10.1%). The most frequent AEs leading to BRV withdrawal were dizziness (1.8%) and memory problems (1.4%). Similar outcomes in terms of effectiveness and tolerability of BRV monotherapy were observed in patients switching from levetiracetam, those with different epilepsy etiologies, and elderly patients. BRV was effective and well tolerated both as first-line monotherapy and following conversion to monotherapy in a real-world setting of patients with epilepsy. The goal of the medical treatment of epilepsy is to ensure best possible patient quality of life, by maximizing seizure control and minimizing medication toxicity. Brivaracetam (BRV) is a new-generation epilepsy treatment that is well tolerated by patients. In our study, monotherapy with BRV reduced seizures in patients who had not received other treatments and in patients who switched from a previous treatment to BRV monotherapy. BRV was well tolerated and also effective in sensitive patients (i.e., the elderly and those who had epilepsy caused by a brain tumor or a brain injury).