The regulatory effect of Liuwei Dihuang Pills (LDP) was studied on cytokines in mice with experimental autoimmune encephalomyelitis (EAE), a model for human multiple sclerosis (MS), induced by immunization with MOG(35-55) and complete Freund's adjuvant (CFA) supplemented with pertussis toxin (PTX). LDP was administrated orally for 40 days, and prednisone acetate (PA) was used as a control. The pathological changes in the spinal cords of mice were observed by light microscope with hematoxylin-eosin (HE) staining and transmission electron microscope (TEM). The protein and mRNA expression of tumor necrosis factor-alpha (TNF-alpha) and transforming growth factor-beta (TGF-beta) in the spinal cords were assessed by immunohistochemistry and RT-PCR assay, and the cyclic adenosine monophosphate (cAMP) in mice plasma was measured by radioimmunoassay (RIA) on days 12, 25 and 40 post-immunization (PI). The results showed that inflammatory cells, demyelination and axonal loss were reduced, and that the protein and mRNA expression of TNF-alpha and the ratio of TNF-alpha/TGF-beta were obviously decreased, to different extents. However, the levels of cAMP were enhanced in LDP-treated groups. These findings suggested that LDP regulates the cytokine balance in favor of T helper 1 (Th1)/regulatory T (Treg) cells, which depend on enhancement of cAMP levels. LDP has a potential role in the treatment of MS and other demyelinating diseases of the central nervous system.