Tacrolimus and cyclosporin are immunosuppressive reagents and have been approved for myasthenia gravis (MG) patients who demonstrate an insufficient response to corticosteroids after thymectomy. MG is an antibody mediated disorder against acetylcholine receptor at neuromuscular junction and autoantibody production is helper T cell dependent. Both drug responses are resulting from binding to the specific cytosolic molecules, which names FK506 binding protein, cyclophilin, respectively. From the perspective of evidence-based medicine, the current evidence level of tacrolimus for treatment of MS is class III, where cyclosporin is class Ib. To establish class I evidence of introducing tacrolimus treatment without prior thymectomy, random controlled clinical trial is under investigation in Japan. Practical usage of these drugs, including induction, maintenance, side effects, and confronting issues are outlined and will be discussed in this review.