Autoimmune mechanisms are implicated in both myasthenia gravis (MG) and multiple sclerosis (MS), and hypothesis of a common immunological mechanism of pathogenesis is supported by the fact that this rare combination of the two diseases occurs more frequently than expected by random association. Although MS is primarily mediated by T lymphocytes and MG primarily involves the destruction of the neuromuscular junction by antibodies, there are evidences that support both cell-mediated and humoral immunity are involved in the pathogenesis of both diseases. Different studies have shown dysfunction of T cells as well as B cells involved in the pathogenesis of both disorders. Previous case reports, mainly present female patients who had a mild presentation of MG, either prior or after diagnosis of MS. In this article, in addition to presenting a unique male patient with a previous diagnosis of MS, who presented with MG crisis, we aimed to review the literature to find the common immunological mechanisms involved in the pathogenesis of MG and MS.