This chapter presents the neurophysiology, pathophysiology, diagnostic testing for action myoclonus-renal failure syndrome (AMRF). AMRF is a form of progressive myoclonus epilepsy first described in four French-Canadian patients belonging to three apparently unrelated sibships living in different regions of Quebec. All patients with AMRF develop action myoclonus and seizures. Most of the patients showed diffuse cerebral and cerebellar atrophy, although some patients had normal computed tomography (CT) and magnetic resonance imaging (MRI) findings. The renal pathology based on renal biopsy specimens showed focal glomerulosclerosis in all patients examined, with features of collapsing glomerulopathy in some. Patients with AMRF have been reported to have normal or low normal β-GC in leukocytes, but very low levels in cultured fibroblasts, and elevated levels in serum. More recently, levetiracetam has been utilized for these patients, and other derivatives are now in clinical trials.