A 34-year-old male presented with fluctuating diplopia, ptosis and motor weakness, who had been suffering from idiopathic thrombocytopenic purpura (ITP) and non-small cell lung cancer (NSCLC). Clinical and laboratory findings confirmed the diagnosis of generalized myasthenia gravis (MG). MG was successfully managed with pharmacologic treatments including an immunosuppressive agent. To the best of our knowledge, this is the first case of MG combined with ITP and NSCLC.