Diagnosis is based on clinical presentation, confirmation of the presence of AChR-Ab, characteristic electromyography findings, and clinical improvement after administration of acetylcholinesterase inhibitors.MG is often associated with thymoma and other autoimmune diseases, but it is rare following allo-HSCT.<h4>Case report</h4>we reports two rare cases of MG after transplantation, including the first case of post-transplantation double-antibody-positive MG. The gene discussed is ACHE; the disease is thymoma.