Psychogenic polydipsia (PPD), a clinical disorder characterized by polyuria and polydipsia, is a common occurrence in inpatients with psychiatric disorders. The underlying pathophysiology of this syndrome is unclear, and multiple factors have been implicated, including a hypothalamic defect and adverse medication effects. Hyponatremia in PPD can progress to water intoxication and is characterized by symptoms of confusion, lethargy, and psychosis, and seizures or death. Evaluation of psychiatric patients with polydipsia warrants a comprehensive evaluation for other medical causes of polydipsia, polyuria, hyponatremia, and the syndrome of inappropriate secretion of antidiuretic hormone. The management strategy in psychiatric patients should include fluid restriction and behavioral and pharmacologic modalities.