Three patients with acute disseminated encephalomyelitis (ADE) and 4 patients in the terminal stages of multiple sclerosis (MS) were subjected to treatment with Cop 1, a synthetic copolymer of amino acids, which had previously been shown to have a beneficial effect in the treatment of experimental allergic encephalomyelitis (EAE). Under the treatment, the ADE patients recovered completely within 3 weeks, but 1 of 2 control cases treated with steroids showed complete recovery as well. The MS patients did not show any significant change in their motor function; however, 2 of them showed some improvement in vision and speech capacity. It is too early to conclude whether this improvement is related to the treatment. No side effect was observed in any of the patients treated with Cop. 1.