Abstract: Objective:To investigate the amyloid deposition components of extracellular matrix （ECM） in leptomenigeal and cortical arterial vessels for analysing the relationship between the pathological changes and cerebral haemorrhage.Methods:Immunohistochemistry was performed on samples obtained from 10 autopsy cases with marked amyloid angiopath （9 Alzheimer's disease and one Down's syndrome） and control group of 8 postmortem cases without encephalopathy. We used a number of primary monoclonal and polyclonal antisera to visulise different components of extracellular matrix, smooth muscle cells and endothelial cells under the microscope. Results:Pronounced reduction of glucose transporter presented in the endothelial cells of the blood vessel of amyloid angiopathies. The deposition of ECM material indicating luminin and collagen IV occured particularly in the media, but the actin was absent. The immunostaining markers of advantitia did not reveal much changes compared with the controls.Conclusion:（1）The prominent pathological changes of cerebral amyloid angiopathes were the degeneration of smooth muscle in the media of arteries and arterioles.（2）Severe amyloid angiopathy with deposition of collagen type IV and luminin and loss of the actin protein in the parts of the media may make the arteries and arterioles more susceptible to ruptures and haemorrhages than vessels in other microangiopathies..