Background: Previous post-hoc analysis of three 12-week, double-blind, placebo-controlled trials showed adjunctive brivaracetam (BRV) reduced focal and secondarily generalized tonic-clonic seizures (SGTCS; Type IC) in patients with baseline SGTCS. This analysis explored long-term efficacy of adjunctive BRV in these patients. Methods: Patients (≥16 years) with focal seizures with SGTCS at Baseline were identified from 12-week double-blind, placebo-controlled trials (NCT00490035/NCT00464269/NCT01261325) and subsequent open-label, long-term follow-up (LTFU) trials (NCT00175916/NCT00150800/NCT01339559). Outcomes were assessed at protocol-specified time-points (up to 60 months). We report post-hoc efficacy data for patients receiving BRV (50–200 mg/day). Results: At double-blind Baseline, 409 patients had SGTCS (mean epilepsy duration: 22.2 years); 28.4%, 38.9%, and 32.8% had 0–1, 2–4, and ≥5 previous AEDs. Baseline median seizure frequency/28 days was 8.1 (focal) and 3.0 (SGTCS only). 325/409 patients (79.5%) entered LTFU. In the 12-month (n=150), 24-month (n=89), 36-month (n=73), 48-month (n=68) and 60-month (n=57) exposure cohorts, median percent reduction from Baseline in SGTCS frequency/28 days was 81.1%, 84.0%, 89.2%, 91.0%, and 90.6%, respectively. ≥50% responder rates for SGTCS were 75.3%, 78.7%, 80.8%, 79.4%, and 78.9%. No safety concerns were identified. Conclusions: Adjunctive BRV (50–200 mg/day) reduced SGTCS frequency during LTFU (up to 60 months) in patients with SGTCS at Baseline.