Paralysis is the complete loss of muscle function for one or more muscle groups. Major causes are stroke, trauma, poliomyelitis, amyotrophic lateral sclerosis (ALS), botulism and Guillain-Barré syndrome.

Paralysis may be localized (in a disorder called Bell's palsy only the nerve responsible from the movements of the facial muscles is affected) or generalized (stroke patients may present with the paralysis of one or both sides of the body).

See also: paraplegia, tetraplegia