Within the last years, diagnostic tools of myasthenia gravis (MG) haveconsiderably improved. The broadened spectrum of pathogenic antibodies defines specific disease subgroups and their individual medical treatment. Implication of more sensitive nuclear based methods for somatostatin binding has widened detection of thymoma suspicious lesions. This implies a definite indication for thymectomy in paraneoplastic MG patients as well as careful surveillance for further paraneoplastic syndromes. In patients with stable disease lacking obvious exercise intolerance in routine clinical testing, objective physical fatigability was present in repetitive movements of proximal muscles using linear trend model. Further, cognitive fatigue could be demonstrated in MG patients which might be caused by frequent sleep related breathing disorders.