This chapter deals with epidemiology, pathology, clinical patterns and diagnosis of multiple sclerosis (MS). It also discusses the treatment options for MS and provides a brief account of other acquired demyelinating diseases. MS is characterized clinically by two major patterns: relapsing-remitting neurological deficits and a progressive neurological deficit. The key diagnostic investigation in MS is magnetic resonance imaging (MRI) scanning, which is abnormal in 95 % of patients. The relationship of seizures to MS activity has been explored and most studies report that about one-third of seizures occur in the context of an acute relapse of MS, sometimes taking the form of focal status epilepticus, usually focal motor status. The treatment of multiple sclerosis falls into three broad categories: symptomatic treatment of the neurological complications of MS, treatment of acute relapses with high-dose corticosteroids, and the use of disease- modifying therapies, including beta-interferon, glatarimer acetate, natalizumab, and mitoxantrone.