Abstract: Objective: To investigate the role of the molar ratio of kaliuretic peptide (KP) and atrial natriuretic peptide (ANP) in acute cerebral vascular diseases(ACVD). Methods: The levels of plasma KP and ANP in 34patients with ACVD at the different period of the course and in 24healthy humans were determined by radioimmumoassay. Results: Compared with control group,the levels of plasma KP in patients with ACVD at the seventh day after onset and plasma ANP in patients with ACVD at each point during the course were significantly increased,and the molar ratio of KP and ANP in patients with ACVD at the first and third days after onset were markedly decreased. Conclusion: KP,ANP and the changes of the ir molar ratio might play an important role in pathogenesis of ACVD.