In an open-label study, 12 patients with refractory MG or who were taking only corticosteroids and required additional immunosuppression received mycophenolate mofetil 1 g twice daily for 6 months. A reduction of three points in a quantified MG score and two points in a manual muscle test or a reduction of 50% in corticosteroid dose defined efficacy. Eight patients improved, beginning after 2 weeks to 2 months. No major side effects were observed.