Objective To investigate the expression and its clinical significance of serum urotensin Ⅱ(UⅡ)and nitric oxide(NO)in chronic cor pulmonale patients in acute exacerbation.Methods Totally 55 cases of chronic cor pulmonale in acute exacerbation(chronic cor pulmonale group)from Respiratory Department of First Affiliated Hospital of Jiamusi University during Nov.2006 to Mar.2007 and 40 healthy volunteers(normal control group)were collected.The levels of serum UⅡ and NO were detected in 55 cases of chronic cor pulmonale in acute exacerbation and 40 normal controls respectively.The condition of everyone's smoking history was collected.Arterial blood gas analysis was made in 37 cases of chronic cor pulmonale in acute exacerbation.The relationship among the levels of serum UⅡ,NO and PaO2,PaCO2,smoking history was observed.Results The levels of serum UⅡ and NO in chronic cor pulmonale in acute exacerbation were significantly higher than those of normal control group(all P