Compositions and methods for the treatment of graft rejection associated with transplantation of tissues and organs include combined treatment involving at least one agent selected from Copolymer 1, a copolymer 1-related heteropolymer or an ordered peptide in combination with at least one additional known immunosuppressive agent. Compositions and methods for the treatment of graft rejection using ordered peptides or ordered copolymer 1-related heteropolymers as monotherapy are also provided.