Angiotensin formed in the renin-angiotensin system is involved in the genesis and development of atherosclerosis and coronary heart disease. It has a negative impact on the process of ischaemization/reperfusion. The renin-angiotensin system is activated during a new myocardial infarction and has an impact on the process of remodelling of the left ventricle after myocardial infarction which causes its dysfunction and heart failure. ACE inhibitors are one of the important means which influence the formation of angiotensin II and thus prevent its action on heart and vessels. They prevent the development of atherosclerosis, reduce the extent of necroses during myocardial infarction and reduce the extent of left ventricular dysfunction. They diminish also stunning of the heart muscle during ischaemia/reperfusion and significantly prolong the patients life after infarction. They do not influence the development of restenosis after percutaneous transluminal angioplasty. ACE inhibitors have a positive effect on heart failure, they reduce the rate of reinfarctions and the mortality rate.