Myasthenia gravis (MG) and tricholeucemia (TL) produce an important immune alteration favoring the appearance of neoplastic and autoimmune disorders. The case of a 53 years old patient who developed type B TL 5 years after the diagnosis of MG is reported. Upon revision of the literature, 37 cases of association of MG and malignant hemopathies, fundamentally lymphoproliferative were found. In general, MG precedes the appearance of the neoplastic process. The autoimmunity and immunodeficiency characteristic of MG probably constitute the pathogenic mechanism leading to the appearance of the neoplastic process.