Myasthenia gravis (MG) is an autoimmune disorder of neuromuscular transmission. MG is primarily caused by autoantibodies specific to the human nicotinic acetylcholine receptor (AChR) and is characterized by fatiguability and weakness of the skeletal muscles. Although oral administration of cholinesterase inhibitors is a useful adjunctive symptomatic therapy, thymectomy and/or immunosuppressant therapy, particularly corticosteroid therapy, are commonly used to improve the symptoms of MG and to prevent the destruction of the neuromuscular junction by AChR antibodies. Currently, MG is treated with several immunomodulating or immunosuppressive agents. Corticosteroids were the first immunosuppressant medications to be used in MG, and remain the most commonly used immune-directed therapy. Here we summarize current knowledge on the efficacy of corticosteroids in treating MG.