Treatment of severe, incapacitating action myoclonus is difficult. Piracetam has been shown to be a very potent antimyoclonic agent, but only at very high, impractical doses, ranging from 24 to 40 g/d. Levetiracetam (LEV), a new antiepileptic drug, is a structurally related compound that has a distinct pharmacological profile and appears to be efficient at much lower doses. We gave LEV, 4,000 mg/d, without titration, to three volunteers with post-anoxic myoclonus (PAM) (one case) and Unverricht-Lundborg disease (two cases), over 2, 2 and 10 weeks, respectively. LEV produced a clear abatement of myoclonus, which is demonstrated on video for the patient with post-anoxic myoclonus, without any unwanted side-effects. These preliminary findings suggest that LEV may have interesting antimyoclonic properties that deserve further investigation.