Lacosamide (LCM) is a new generation antiepileptic drug. It has only been available in Asia in recent years. A retrospective study at two hospitals in Hong Kong was performed to investigate the post-marketing efficacy and tolerability of the drug. A total of 81 subjects were recruited, among which 88% had drug-resistant epilepsy. The most common type of epilepsy was focal with unknown etiology. All patients used LCM as adjunctive therapy. The 50% responder rate was 42% at 12 weeks after achievement of maximal dose of LCM. No specific factor correlated with responsiveness including concomitant enzyme-inducing or sodium channel blocking anticonvulsants. Withdrawal rate within first 12 weeks after drug initiation was 14% while that at any time upon follow-up was 23%. Two cases of uncommon adverse reaction of myoclonus were also reported. The mechanism was postulated to be the sodium channel inhibiting action of LCM. Our study has shown LCM to have comparable efficacy and tolerability in post-marketing experience when compared with the landmark randomized controlled trials.