Hypertension is the leading cause of cardiovascular disease worldwide. Prior to 1990, population data suggest that hypertension prevalence was decreasing; however, recent data suggest that it is again on the rise. In 1999-2002, 28.6% of the U.S. population had hypertension. Hypertension prevalence has also been increasing in other countries, and an estimated 972 million people in the world are suffering from this problem. Incidence rates of hypertension range between 3% and 18%, depending on the age, gender, ethnicity, and body size of the population studied. Despite advances in hypertension treatment, control rates continue to be suboptimal. Only about one third of all hypertensives are controlled in the United States. Programs that improve hypertension control rates and prevent hypertension are urgently needed.