Cigarette smoking is a major cause of coronary heart disease, stroke, aortic aneurysm, and peripheral vascular disease. The risk is manifest both as an increased risk for thrombosis of narrowed vessels and as an increased degree of atherosclerosis in those vessels. The cardiovascular risks owing to cigarette smoking increase with the amount smoked and with the duration of smoking. Risks are not reduced by smoking cigarettes with lower machine-measured yields of tar and nicotine, but those who have only smoked pipes or cigars seem to have a lower risk for cardiovascular diseases. Cessation of cigarette smoking reduces disease risks, although risks may remain elevated for a decade or more after cessation.