Loss of expression of the 3G11 epitope, present on disialoceramide that is predominantly found on CD4(+) T cells, has been associated with a regulatory T cell (Treg) phenotype and tolerance induction in experimental autoimmune encephalomyelitis (EAE). Here we report that treatment with anti-3G11 mAb shifts the immune response from pro-inflammatory to tolerogenic and suppresses both chronic-progressive and relapsing-remitting EAE. This therapeutic effect can be achieved at different stages of EAE. Treatment with anti-3G11 mAb increased the proportion of Foxp3(+)CD25(+)CD4(+) Tregs and IL-10 production while inhibiting production of pro-inflammatory cytokines and responsiveness to IL-2 and decreasing the proportion of T(h)17 cells. The effect of anti-3G11 mAb was diminished in IL-10(-/-) mice, indicating that this cytokine mediates some of its effects. As 3G11 belongs to the ganglioside family, which is expressed on the surface of both murine and human CD4(+) T cells, targeting this class of molecules may provide a novel approach for treating autoimmune diseases.