In a series of 1460 consecutive patients admitted to an "acute" stroke unit, 10 patients (0.7%) were found to have a metabolic encephalopathy which mimicked stroke. Of these, three had hypoglycaemia, four had hyperglycaemia, three had hyponatraemia, and one had suffered from hypoxia. Metabolic disorders should be excluded in all patients with a diagnosis of suspected stroke, especially if the presentation is associated with a confusional state or focal seizures. The conventional symptoms and signs of the metabolic disorders may be minimal or absent. The relative rarity of these disorders among patients with suspected stroke is overshadowed by the importance of early recognition and treatment, in order to minimize morbidity and mortality.