The prevalence of obesity in industrialized countries has reached epidemic proportions, with about one in three people being obese and another one in three people being overweight and at risk of developing obesity. In recent years, obesity has gained the traditional tetrad of cardiovascular risk factors of smoking: hypertension, dyslipidemia, and dysglycemia. Attention has also focused on the importance of abdominal (or central) obesity as a determinant of cardiovascular risk, independent of the body mass index. In addition to effects on coronary artery disease, obesity has an effect on cardiovascular disease, including stroke, ventricular function, peripheral arterial disease, and venous thromboembolism. The objectives of this review are to summarize the effects of obesity on cardiovascular disease, and the possible mechanisms for these associations, and to investigate the effects of weight-loss interventions on the burden of cardiovascular disease. Large ongoing clinical outcome trials, such as the SOS study, the Look-AHEAD trial, or the SCOUT study, should provide important information on the effects of surgical and nonsurgical obesity treatment on cardiovascular morbidity and mortality.