Several pathologic reports have indicated the occurrence of extrapontine sites of myelinosis associated with electrolyte disturbance and its rapid correction. Clinical evidence of the presence of such lesions, however, have rarely been described. We report a case of a 50-year-old man who following rapid correction of electrolyte imbalance developed a profound striatal syndrome. The clinical manifestations, the course of his illness as well as response to therapy, confirmation of lesion sites by magnetic resonance imaging (MRI), and abnormalities on visually evoked potentials are described in detail.