Endocrine or metabolic diseases can be major causes of neurological disorders such as disturbance of consciousness, psychosis, epilepsy, involuntary movements, and cerebellar ataxia. Such endocrine diseases widely vary among impairments of subthalamus/pituitary gland, thyroid/parathyroid, adrenal gland, and pancreas. Metabolic diseases, including unusual blood sugar, hyperammonemia, and electrolyte abnormalities, also cause neuropsychiatric disorders. Particular neurological signs, e.g. mounding phenomenon in hypothyroidism or Trousseau's sign in tetany, can be a key for the early–diagnosis of endocrine/metabolic diseases. The basic laboratory findings, e.g. hyponatremia, or radiological findings, hyperintensity in the basal ganglia in hyperammonemia are also helpful in making a different diagnosis. As delays in the diagnosis and treatments of these neurological patients associated with endocrine/metabolic diseases may cause irreversible brain damage, it is imperative for clinicians or medical staffs to carefully exclude the possibility of latent endocrine/metabolic diseases.