OBJECTIVES: Economic evaluation of Lacosamide (LCM) and standard treatment with commonly used antiepileptic drugs (ST) vs. ST alone in the Finnish setting. LCM is a new antiepileptic drug, indicated for adjunctive treatment of partial-onset seizures (POS) with or without secondary generalisation in patients aged 16 years and older. METHODS: A probabilistic decision tree based cost-effectiveness analysis (CEA) with second-order Monte Carlo simulation and a 2-year time-frame was performed in Excel from the Finnish societal perspective (productivity losses and VAT excluded). The efficacy data were obtained from the LCM-trials, and the Finnish costs (inpatient, outpatient, GP, laboratory, drug) and utilities from published studies. Budget impact modelling (BIM) with a five year time-frame was done to assess the net monetary impact of LCM launch to the refractory epilepsy budget. Only drug costs were included in BIM. Conservatively, generic prices were used in all analyses. RESULTS: According to CEA, LCM+ST was associated with an incremental cost of €945 (mainly related to seizure management and drug acquisition), a gain of 0.040 QALYs and 8.92 seizures avoided compared to ST alone. LCM+ST was associated with a cost of €23,396 per QALY gained and €106 per seizure avoided compared to ST alone. According to the cost-effectiveness acceptability frontier, the probability of LCM’s cost-effectiveness was 67.9% and 85.6% with €30,000 and €50,000 per QALY gained, respectively. The results were robust in sensitivity analyses. According to BIM, the expected annual budget increase due to launch of LCM is €0 in 2008, €7,653 in 2009, €47,350 in 2010, €134,949 in 2011, and €232,609 in 2012. The relative increase in the annual epilepsy budget due to LCM is 0.08% in 2009, 0.46% in 2010, 1.31% in 2011, and 2.23% in 2012. CONCLUSIONS: LCM is a valuable option for POS treatment because of its potential cost-effectiveness and low budget impact.