Psychogenic polydipsia with associated hyponatremia is a potentially fatal condition observed in patients with chronic psychiatric illness, especially schizophrenia. Recognition and management of this condition are difficult, as patients are uncooperative and secretive about their water intake, but are important in terms of the associated complications. Different strategies, including involuntary fluid restriction and use of various pharmacological agents, such as demeclocycline, propranolol, captopril, and naloxone, have been used for the treatment of this condition with inconsistent results. Antipsychotics have also been used in the treatment of polydipsia; however, their role is not clear as there are reports of antipsychotics both improving and causing polydipsia. Typical antipsychotics have been associated with exacerbation of polydipsia, whereas clozapine has been associated with its improvement. The efficacy of risperidone in the treatment of this condition is controversial, as negative results have been reported. Herein we present a schizophrenia case with polydipsia and hyponatremia that was successfully treated with risperidone.