The majority of hypertensive patients fall into the borderline and mild groups. A smaller percentage of the hypertensive population falls into the groups with persistent elevations in diastolic blood pressure of 105 mm Hg or higher. However, they are a most important group because treatment has been effective in reducing their high risk of developing major complications. In mild hypertension, the physician will treat those who are at increased risk as judged by age, race, sex, target organ damage, family history, hyperglycemia, and hypercholesteremia. Even though most mild and borderline hypertensive patients are not treated, they should be followed up since some of these patients may progress to a more severe stage of hypertension and should then be treated.