We present a 33 year-old man, admitted because of transient deterioration of visual acuity. Magnetic resonance imaging showed diffuse central nervous system (CNS) demyelination, which largely resolved spontaneously within 4 months. The patient fulfilled the diagnostic criteria of APS type III, having autoimmune thyroiditis and alopecia universalis. In this patient, autoimmune activation against CNS antigens is thought to be the cause of reversible CNS demyelination. (C) 2002 Elsevier Science B.V. All rights reserved.