Guillain–Barré syndrome, an acute autoimmune inflammatory polyneuropathy, is the most frequent cause of acute onset flaccid paresis. Various sources report its incidence of 1–4/100,000 individuals per year. A triggering factor in most cases is a previous respiratory or gastrointestinal tract infection. Apparently, via the molecular mimicry mechanism, antibodies against bacterial or viral antigens are formed and bind with similar epitopes in the peripheral nervous system. The clinical picture is highly diversified and may range from slight muscle weakness within the feet to full-blown tetraplegia with respiratory failure. The typical course of the disease consists of the progressive phase, the plateau phase and the recovery phase, lasting even 6–14 months. The diagnosis is based on the criteria published in 1978. They encompass clinical signs and symptoms as well as electrophysiological and pathomorphological parameters. A crucial sign leading to the diagnosis is progressive flaccid paresis of more than one limb with the absence or reduction of tendon reflexes. The treatment involves plasma exchange and intravenous immunoglobulin. The use of glucocorticosteroids, interferon beta, rituximab and eculizumab requires further investigation. Moreover, symptomatic treatment, kinesiotherapy, respiratory physiotherapy, thromboembolic prophylaxis, nutritional therapy and pain management are also very important. Prognosis is in most cases favourable, but mortality ranges from 4 to 15% despite appropriate treatment and intensive care. The aim of this article is to sum up current information about Guillain–Barré syndrome and to emphasise the relevance of this disease, which requires further investigation in both paediatric and adult patients.