Autoimmune diseases of the peripheral nervous system are common in pediatrics. Guillain-Barre syndrome, juvenile myasthenia gravis, and juvenile dermatomyositis are the most important. Their common pathogenesis involves the action of specific autoantibodies which are frequently triggered by viral or bacterial infection. Acute inflammatory demyelinating polyneuropathy is the most frequent pathological feature. There is also a motor axonal form. Both have a progressive ascending clinical course. The specific treatment is immunoglobulin 2 g/kg. Juvenile myasthenia gravis is expressed by ocular signs and generalized and fluctuating fatigability. It can involve respiratory functions triggering a myasthenic crisis. It is treated with anticholinesterase agents, corticosteroids, immunoglobulins, and immunosuppressants. Thymectomy has recently shown effectiveness. Juvenile dermatomyositis is expressed by skin and muscle signs. Elevated muscle enzymes, muscle biopsy, and magnetic resonance imaging contribute to the diagnosis. It is treated with corticosteroids, immunoglobulins, and immunosuppressants. All three disorders, Guillain-Barre, juvenile myasthenia gravis, and juvenile dermatomyositis have a good prognosis.