INTRODUCTION: Pregabalin efficacy and safety as an adjunctive treatment for partial seizures was evaluated using an open-label, flexible-dose.STUDY DESIGN: In 98 adults with refractory partial epilepsy taking 1-3 anti-epileptic drugs with ≥2 seizures during an 8-week baseline period.METHODS: Pregabalin was increased to ≤600 mg/day during a 9-week dose optimization period with dosage maintained for 12 additional weeks. Primary endpoint was the percentage change in partial seizure frequency between the 8-week baseline and 12-week observation period.RESULTS: Pregabalin treatment was associated with a significant reduction in partial seizure frequency: median percent change in partial seizure frequency from baseline to 12 weeks was -33% and -22% in patients with a baseline seizure frequency of ≤3 and >3 per 28 days, respectively. The 50% and 75% responder rates were 41.94% (95% CI: 31.91-51.96) and 30.11% (95% CI: 20.78-39.43), respectively. Nineteen percent of subjects were seizure-free throughout the last 12 weeks. Pregabalin administration resulted in a significant reduction in anxiety (mean reduction in Hospital Anxiety and Depression Scale scores of 1.68 units, 95% CI: -2.60 to -0.76). Most patients were much improved or very much improved on Patient Global Impression of Change (53.8%) and Clinical Global Impression of Change (53.8%). The most frequently self-reported adverse events (AEs) were mild or moderate somnolence (20.4%) and dizziness (5.1%) with a low AE discontinuation rate (5.1%).CONCLUSIONS: The efficacy and side-effect profile of pregabalin were similar to previous pregabalin double-blind, controlled studies. Additionally, pregabalin, as an add-on treatment for partial epilepsy, exhibits significant anti-anxiety properties.