Myasthenia gravis (MG) is a common autoimmune disorder characterized by the presence of pathogenic antibodies directed against the acetylcholine receptor. Patients present with variable degrees and distribution of fluctuating weakness, at times life-threatening. Clinical manifestations, establishment of diagnosis, the natural history of MG, and therapeutic options are herein reviewed with an emphasis on pearls and pitfalls of clinical relevance. Far less common is Lambert-Eaton syndrome (the myasthenic syndrome), another autoimmune disorder due to the presence of antibodies directed against the PQ-type voltage-gated calcium channels. Clinical features and treatment issues of these and other disorders of neuromuscular transmission are reviewed.