A study was made of the blood pressure in 2998 males and 2759 females of the white population of the United States, who were apparently healthy and without known heart disease. The mean blood pressure was 145/82 for men and 156/84 for women. The mean systolic and diastolic blood pressures do not show a continuous rise with age after 65. In men the peak systolic is 145-146 mm Hg, in women, 159 mm Hg. After the age of 74, the systolic pressure declines slowly in women, but remains essentially constant in men. The mean diastolic pressure shows little variation from ages 65-80 and tends to decline thereafter. Frequency distribution curves of the systolic and diastolic pressures, at all ages, have the basic pattern of a bell-shaped curve. In both sexes the curves have a positive skewness larger and more consistent in the systolic than in the diastolic pressures. A single set of blood pressure standards was computed for each sex, applicable to the entire apparently healthy population from age 65 to over 100. These computations place the middle 80% range ([plus or minus] 1.282 sigma) in males at [image], and females [image]. The middle 95% range ([plus or minus] 2 sigma) in males is [image], in females [image].