Desmopressin is a synthetic replacement for vasopressin, which is used to reduce perioperative blood loss. However, seizure attacks were observed in patients after administration of desmopressin. Here, we reported two cases of adult Chinese patients experienced generalized tonic-clonic seizures associated with severe hyponatremia caused by intravenously administered desmopressin after surgery. The patients' neurological conditions returned to baseline quickly and completely following discontinuation of desmopressin, control of the seizures, and fluid intake restriction. These cases illustrate the importance of periodic monitoring of electrolyte concentrations and fluid intake during use of desmopressin.