In Tecumseh, Mich, we obtained blood pressure (BP) self-determination data in 608 healthy adults (327 men, 281 women; average age, 32.6 +/- 3.5 years) representing a wide range of educational backgrounds. The average (+/- SD) home BP (average 12.7 readings over 1 week) was 120.7/74.8 +/- 10.4/8.6 mm Hg for men and 110.9/69.9 +/- 10.1/7.7 for women. One hundred thirty-three subjects remeasured their home BP 1 year later and a strong correlation between the two readings was obtained (r = .70). Large-scale BP self-determination is feasible. Based on the BP distribution in Tecumseh, the upper limit of normalcy for home BP (2 SDs above the mean) is 142/92 mm Hg for men and 131/85 mm Hg for women.