The progressive myoclonus epilepsies (PMEs) are a rare group of disorders with varied causes manifested by myoclonus, often activated by movement or action, but also occurring at rest. The form of PME is particularly striking in many family members affected by autosomal dominant Alzheimer disease linked to chromosome 14. The presenting features are cognitive decline with prominent seizures and myoclonus. Myoclonus is frequently described as an early feature of patients with amyloid precursor (16) protein gene mutation pedigrees who have limb dyspraxia, brisk reflexes, visual disorientation, and slow gait. Toxic causes of myoclonus include the sialysis syndrome characterized by myoclonus, asterixis, speech disorder, seizures, personality changes, and progressive dementia. The use of serotonin reuptake inhibitors commonly used as antidepressants may lead to severe myoclonus described with the use of citalopram and risperidone. Cephalosporin toxicity, levetiracetam accumulation in renal failure, amlodipine and nifedipine can induce acute myoclonic jerking without convulsive seizures.