OBJECTIVES: To gather data on clinical effectiveness of lacosamide add-on therapy to standard antiepileptic drugs (AEDs) in the Czech Republic. These data were intended as inputs for a cost-effectiveness analysis. METHODS: A retrospective multicenter (n=40) data collection of patients with epilepsy treated with lacosamide for 6 months in clinical practice was performed. Information on the number of seizures and concomitant AEDs before and after lacosamide treatment was observed. In this analysis patients reporting at least a 50% reduction in seizure number 3 months after lacosamide treatment were considered responders. Adverse events reported after initiating lacosamide treatment were collected. RESULTS: In total, data from 409 patients were collected, 403 had complete data that were analyzed. Mean (SD) age was 40.4 (±14.2) years and the mean (SD) time since diagnosis 18.7 (±12.8) years. In 91% of patients lacosamide treatment was initiated because of resistance to previous AEDs. Most patients suffered from partial (44.2%), secondary generalized (20.1%) or both (34.0%) types of seizures, or other (1.7%). Following lacosamide administration the mean (median) number of seizures decreased from baseline of 40.3 (12.0) to 25.9 (7.0) (per 3 months). Median (mean) number of seizure reduction was equal to 41% (30%), and 45% were responders. Adverse events occurred in 79 pts (19.6%), with somnolence (6.2%) and dizziness (5.5%) most frequently reported. During lacosamide administration, a decrease in concomitant AEDs number was observed. The mean number per patient decreased from 2.2 to 1.7, as did concomitant AEDs used before and after lacosamide administration: levetiracetam (39% vs. 33%), lamotrigine (38% vs. 32%), carbamazepine (34% vs. 29%), valproate (33% vs. 28%) and zonisamide (17% vs. 8%). CONCLUSIONS: Results confirm the effectiveness of lacosamide in the reduction of seizure frequency in clinical practice. In addition, findings suggest that adding lacosamide may lead to a reduced use of other concomitant AEDs.