Cardiovascular disease is the second highest cause of death in the UK. This chapter outlines the function of the heart and circulation before describing coronary heart disease, heart failure, peripheral arterial disease and cerebrovascular disease in more detail. UK epidemiological data and extracts from qualitative research illustrate the burden of cardiovascular disease to individuals and the nation. The chapter examines atherosclerosis in depth, focusing on the causes of atheroma and the causes of damage to blood vessels and blood flow. These include high blood cholesterol, diet, high blood pressure (hypertension), high blood glucose, tobacco/e-cigarettes, physical inactivity, sedentary behaviour, alcohol, chronic stress, adverse childhood experiences, air pollution and excess body/abdominal fat (obesity). The influence of the socio-economic and physical environment is illustrated by data showing inequalities in cardiovascular disease and risk factors across quintiles of deprivation in the UK. The non-modifiable risk factors age, ethnicity, family history/genetics and sex are outlined. The chapter concludes with priorities for the primary, secondary and tertiary prevention of cardiovascular disease, and notes that more than half of UK cardiovascular disease is thought to be avoidable.