The behavioral effects of endocrinopathies suggest many different psychiatric illnesses, and the neuropsychiatric effects can be among the first manifestations of endocrine disease. This chapter lists out the endocrine diseases that include: hypothyroidism, hyperthyroidism, hyperparathyroidism, hypoparathyroidism, adrenal disorders, hypocortisolism, diabetes mellitus and hyperprolactinemia. Hypothyroidism is treated by thyroid replacement. Acute Hashimoto's encephalopathy can be treated with glucocorticoids. Antidepressants can be combined with thyroid hormone for depression that does not respond to thyroid replacement alone. In most cases, psychiatric symptoms are resolved when hyperparathyroidism is treated and serum calcium levels return to normal. Primary hyperparathyroidism is treated by surgical resection of the adenoma or parathyroidectomy. Suitable replacement antipsychotics can be found for patients at higher risk with schizophrenia and bipolar disorder with propensity to weight gain and metabolic syndrome. Cognitive behavioral therapy is also effective for depression and improves hemoglobin A1c levels.