Copaxone was launched in Israel and the US for treatment of relapsingremitting multiple sclerosis. The amino acid polymer is prepared from the Ncarboxyanhydrides of Tyr, Ala, γ-benzylglutamate and ε,N-trifluoroacetyllysine followed by deprotection. Structurally, the random polymer, with a residue molar ratio of 6.0:1.9:4.7:1.O=Ala:Glu:Lys:Tyr, simulates myelin basic protein (MBP). This gives it immunomodulating and immunosuppressive activity (antigen specific so not a general immunosuppressive). The mechanism involves binding to MHC class Ⅱ (I-A/DR) molecules which results both in competition with myelin antigens for T-cell activation and in induction of specific suppressor cells of the Th2 type. Therefore, the antigenspecific interaction gives rise to a reduced probability of long-term damage to the immune system. The competition with MBP and other myelin-associated antigens inhibits T-cell responses to MBP, and the binding occurs with high efficiency, fast rates and is non-species specific. It resulted in a 29% reduction in relapse rate and is most effective in patients with less accumulated neurologic disability.