Investigations of the natural history of blood pressure have generally evaluated mean systolic and diastolic pressure changes. While information, this information is not directly applicable to clinical practice settings, in which patients are usually classified as normotensive or hypertensive. We measured the actual incidence of hypertension, using two different definitions, in an ambulatory elderly population of 2,584 individuals over an 8-year period. Using the less stringent blood pressure definition (systolic blood pressure greater than 140 mmHg and diastolic blood pressure greater than or equal to 90 mmHg), 884 (34.2%) participants were normotensive and 1,700 (65.8%) were hypertensive at an initial screening. The average annual incidence of hypertension over the subsequent eight years was 13.2%, and life tables demonstrated a gradual risk of developing hypertension. The development of hypertension was not associated with gender or age; while older age groups had a greater chance of developing hypertension than younger, the difference did not reach statistical significance.