Psychiatric patients presenting with chronic psychogenic polydipsia are often difficult to treat with standard psychiatric interventions. Pharmacologic intervention was attempted in three patients and was successful in one. One patient had a significant and sustained reduction of water intake while on 160 mg of propranolol. One patient did not improve with either propranolol or captopril while a third patient showed no improvement of serum sodium with demeclocycline nor reduction of water intake with propranolol. The potential mechanisms by which these pharmacologic agents might alter thirst in patients with primary polydipsia are discussed.