A case of psychogenic polydipsia is presented. A 40 year old female was brought to the emergency room after a sudden seizure at home. The patient had spontaneous eye opening, was making incomprehensible sounds and had abnormal and agitated flexion of the limbs. Severe cerebral edema was seen on the computed tomogram. The patient was found to have hypotonic polyuria and hyponatremia. Two months previously, the patient had stopped taking bromazepam (a benzodiazepine) and on the advice of a neighbour had taken plenty of water to avoid withdrawal symptoms. The diagnosis and therapy are discussed.