Myasthenia gravis is a rare autoimmune disorder in which antibodies form against acetylcholine nicotinic postsynaptic receptors at the myoneural junction. Psoriasis vulgaris is a chronic, recurring, and an inflammatory skin disease. Myasthenia gravis and psoriasis are both autoimmune diseases and correlated with specific human histocompatibility antigens. In this report, a 53-year-old woman who has myasthenia gravis accompanied with psoriasis vulgaris is presented. To conclude, this association is extremely rare and the pathogenetic etiology was thought to depend on a generalized immunological disturbance.