Cardiovascular disease is a major cause of disability and premature death throughout the world, and contributes substantially to the escalating costs of health care. The underlying pathology is atherosclerosis, which develops over many years and is usually advanced by the time symptoms occur, generally in middle age. Acute coronary and cerebrovascular events frequently occur suddenly, and are often fatal before medical care can be given. Modification of risk factors has been shown to reduce mortality and morbidity in people with diagnosed or undiagnosed cardiovascular disease. This publication provides guidance on reducing disability and premature deaths from coronary heart disease, cerebrovascular disease and peripheral vascular disease in people at high risk, who have not yet experienced a cardiovascular event. People with established cardiovascular disease are at very high risk of recurrent events and are not the subject of these guidelines. They have been addressed in previous WHO guidelines. Several forms of therapy can prevent coronary, cerebral and peripheral vascular events. Decisions about whether to initiate specific preventive action, and with what degree of intensity, should be guided by estimation of the risk of any such vascular event. The risk prediction charts that accompany these guidelinesb allow treatment to be targeted accord- ing to simple predictions of absolute cardiovascular risk. Recommendations are made for management of major cardiovascular risk factors through changes in lifestyle and prophylactic drug therapies. The guidelines provide a framework for the development of national guidance on prevention of cardiovascular disease that takes into account the particular political, economic, social and medical circumstances.