Myasthenia gravis is an autoimmune disorder of neuromuscular transmission. It is characterised by muscular weakness and fatiguability. Extrinsic ocular muscles are frequently involved at the onset of the disease; in about 15% of cases clinical signs remain confined to these areas, while in the other patients weakness becomes generalised. Diagnosis relies on clinical history and signs, improvement on anticholinesterase injection, electromyographic signs of impaired neuromuscular transmission and serum antiacetylcholine receptor (anti-AChR) antibody titration. Apart from the anti-AChR antibody assay, no single test is specific for myasthenia gravis; it is rather their combined results that can confirm diagnosis. The therapeutic approach varies from patient to patient and, as far as possible, should be adapted to each individual. Symptomatic drugs such as anticholinesterases improve muscle strength but seldom restore it to normal. Immunosuppressive therapy is very effective but entails the risk of severe adverse effects. Thymectomy improves the course of the disease and can increase remission rate; short term treatments are of benefit in the management of myasthenic emergencies.