Objective To investigate the effects of Polygoni Cuspidati Rhizoma et Radix(PCRR) and its ingredient resveratrol(Res) on experimental autoimmune myasthenia gravis(EAMG). Methods EAMG was induced in Lewis rats by the immunization of a synthetic peptide corresponding to region 97–116 of the rat acetylcholine receptor(ACh R) α subunit(R97-116). EAMG rats were randomly divided into PCRR group, Res group, and control(C) group, and were ig administered respectively with PCRR(2 g/kg), Res(20 mg/kg), and DMSO(0.4 m L/kg) every day from day 5 after immunization to day 42. Clinical evaluation, lymphocyte proliferation, cytokines, and anti-97-116 antibodies were performed for examination of their therapeutic effects. Results Treatments with PCRR and Res significantly ameliorated clinical symptoms, down-regulated TNF-α and up-regulated IL-10 in serum and culture supernatants of lymphocytes stimulated with R97-116, and decreased levels of anti-R97-116 Ig G1 and Ig G2 a in serum compared with C group. Unexpectedly, PCRR but not Res inhibited lymphocyte proliferation compared with C group. Conclusion PCRR and Res ameliorating EAMG is associated with suppressing immune response, and indicates a therapeutic potential for EAMG and even human myasthenia gravis(MG). Res may be the main effective ingredient from PCRR ameliorating EAMG, but further experiments are necessary. Objective To investigate the effects of Polygoni Cuspidati Rhizoma et Radix (PCRR) and its ingredient resveratrol (Res) on experimental autoimmune myasthenia gravis (EAMG). Methods EAMG was induced in Lewis rats by the immunization of a synthetic peptide corresponding to region 97-116 (R97-116). EAMG mice were randomly divided into PCRR group, Res group, and control (C) group, and were implanted respectively with PCRR (2 g / kg), Res (20 mg / kg), and DMSO (0.4 m L / kg) every day from day 5 after immunization to day 42. Clinical evaluation, lymphocyte proliferation, cytokines, and anti-97-116 antibodies were performed for examination of their therapeutic effects. Results Treatments with PCRR and Resistant ameliorated clinical symptoms, down-regulated TNF-α and up-regulated IL-10 in serum and culture supernatants of lymphocytes stimulated with R97-116, and decreased levels of anti-R97-116 Ig G1 and Ig G2 a in serum compared with C group. Unexpectedly, PCRR but not Respiratory lymphocyte proliferation compared with C group. Conclusion PCRR and Res ameliorating EAMG is associated with suppressing immune response, and indicates a therapeutic potential for EAMG and even human myasthenia gravis (MG). Res may be the main effective ingredient from PCRR ameliorating EAMG, but further experiments are necessary.