Objective To study the effect of laboratory mental stress on plasma levels of angiotensinⅡ( AngⅡ),aldosterone (ALD) , atrial natriuretic peptide ( ANP) and NO in healthy subjects with different type of behavior. Methods Blood pressure ,plasma AngⅡ, ALD and ANP concentration and the level of serum NO were observed before and after mental arithmetic test. Results Levels of Blood pressure, plasma AngⅡ and ALD increased significantly (P