Eosinophilia myalgia syndrome (EMS) is a toxin-induced illness that pr
ovides a model for the understanding of idiopathic immune-mediated dis
eases that have overlapping features. The clinical development and chr
onic sequelae of EMS, its relationship to related disorders, and the a
ccumulating data suggesting an important role for immune mechanisms in
the pathogenesis of this disease are reviewed in this article.