Myasthenia gravis (MG) is an autoimmune disease that occurs as a consequence of anti-acetylcholine (Ach) antibodies specifically targeting postsynaptic Ach receptors (AchR). This leads to the evolution of the classic symptoms of the disease, which range from mild symptoms of diplopia, muscle fatigue with repetitive movement up to severe affection of the respiratory muscle. The disease can occur as an isolated finding or co-exist with a concomitant thymic tumor or hyperplasia. Careful diagnosis is crucial for the development of the management plan. Nearly 10–15% of MG cases coexist with a thymic pathology and in these cases, surgical resection leads to the resolution of symptoms. Although thymomatous MG occurrence is non-heritable, its polygenic nature accounts for its rare familial variant. In this case, we report a family of three brothers with familial thymomatous MG who underwent thymectomy and improved after thymic surgical resection. Myasthenia gravis can occur as an isolated finding or as an association of thymic pathology. Careful discrimination between the two should be made for the elaboration of a management plan. Familial variant thymomatous myasthenia gravis is exceedingly rare. A familial survey is crucial for its management.