Background Cathepsin L (CTSL),a member of the cysteine protease cathepsin family,is an important Lyso-somal peptidase,which has the best activity in an acidic environment and less activity in a neutral environment.Its physiological function involves proteolysis,antigen presentation,T cell development,cell apoptosis,and em-bryonic development,and is closely related to the occurrence and development of various types of cancer,cardio-vascular disease,and kidney disease.In this paper,the role and mechanism of CTSL in the development of athero-sclerosis,coronary heart disease,restenosis,abdominal aortic aneurysm,and dilated cardiomyopathy were briefly reviewed.