Abstract Ten years ago, the discovery of a deficit of acetylcholine receptors (AChRs) at neuromuscular junctions of patients with myasthenia gravis (MG) 17, and the development of an experimental animal model of the disease 33, shed new light on a human disorder that was first described exactly 300 years earlier by the great physiologist Thomas Willis. During the past decade, rapid progress has been made in our understanding of the pathogenesis of MG and the ability to treat it. It is now widely accepted that the basic defect in MG is a decrease in the number of junctional AChRs due to an antibody-mediated autoimmune response. Several mechanisms have been defined by which autoantibodies reduce the number of available AChRs. However, there is still much to be learned about MG: it is not yet clear how the autoimmune response is triggered initially or how it is subsequently maintained. Furthermore, though virtually all myasthenic patients can now be effectively treated, the ultimate goal of a specific cure has yet to be realized.