Abstract: Objective: To study the incidence rate and clinical features of hypernatremia in severe stroke and provide the evidences for therapy.Methods: The clinical data and clinical prognosis of 156 admitted patients with severe stroke were analyzed retrospectively.The incidence rate of hypernatremia in 24 hours,>24 to 72 hours and >72 hours to 1 week were analyzed.The relationships between hypernatremia and the types of stroke,focus places,the neurological deficit and clinical prognosis were also analyzed.Results: Among all patients 25 patients were accompanied with hypernatremia,the incidence rate of hypernatremia was 16.03%.Sixteen patients with hypernatremia were happened in 72 hours after stroke,and 2 patients were accompanied with severe hypernatremia.And the iatrogenic factor maybe was the main risk factor.Nine patients with hypernatremia were happened after 72 hours,of which 5 patients were accompanied with severe hypernatremia.Hypernatremia had the relationship with focus places of stroke(especially in brainstem,thalamus and cerebellum),the neurological deficit and prognosis(P<0.05-P<0.01),and had no relationship with types of stroke(P>0.05).Conclusions: The iatrogenic factor and the injury on brainstem,thalamus and cerebellum are the reasons for hypernatremia after stroke.The emergence of hypernatremia is considered as an important index which estimates the state of stroke and clinic prognosis.