Expression of CCR6 and its ligand, CCL20, are increased in the colon of humans with inflammatory bowel diseases and mice with experimental colitis; however, their role in disease pathogenesis remains obscure. In this study, we demonstrate a role for CCR6 on regulatory T (Treg) cells in the T cell-transfer model of colitis. Rag2−/− mice given Ccr6−/− CD4+ CD45RB high T cells had more severe colitis with increased IFN-γ–producing T cells, compared with the mice given wild-type cells. Although an equivalent frequency of induced/acquired Treg (iTreg) cells was observed in mesenteric lymph nodes and colon from both groups, the suppressive capacity of Ccr6−/− iTreg cells was impaired. Cotransfer studies of wild-type or Ccr6−/− Treg cells with CD4+ CD45RB high T cells also showed a defect in suppression by Ccr6−/− Treg cells. CCR6+ Treg cells were characterized as Ag-activated and IL-10–producing in the steady-state and preferentially migrated to the colon during inflammation. Thus, we conclude that CCR6 expression on Treg cells was required for the full function of Treg cell-mediated suppression in the T cell-transfer model of colitis. CCR6 may contribute to the regulation of colitis by directing its function in Ag-specific, IL-10–producing iTreg cells to the inflamed colon.