Glatiramer acetate (GA) is a mixture of synthetic polypeptides composed of four aminoacids. GA is very effective in suppression of experimental autoimmune encephalomyelitis (EAE), the animal model of multiple sclerosis (MS). Various mechanisms of action of GA have been proposed, but the most important is probably the induction of antigen-specific suppressor T cells. Class one clinical trials have demonstrated that GA reduces the relapse rate and the accumulation of disability in relapsing-remitting (RR) MS. The positive effects on disease activity and disease progression are explained by the reduction of the number and volume of the active lesions as showed by Magnetic resonance imaging (MRI) studies. Moreover new MRI techniques suggest that GA may also have some neuroprotective effects. The drug is usually well tolerated with modest side effects. In vitro and in vivo animal studies have shown that GA is devoid of teratogenic or mutagenic effects. GA is a good alternative to interferon beta for treatment of RR-MS.