The first case of central pontine myelinolysis in Scandinavia is presented. A premortem diagnosis was established on the basis of the history of chronic alcoholism, the picture of severe electrolyte disturbance and the development of the neurological syndrome. The postmortem findings verified the clinical diagnosis. A possible aetiological mechanism is postulated. The cause is believed to be a damage to the energy dependent electrolyte transport across the cell membrane, resulting in a cytotoxic oedema and death of the oligodendroglial cells of the brainstem which are particularly vulnerable.