Blood pressure was measured in 4186 children aged 5 to 7 years in 9 British towns. 3 towns had high, 3 had intermediate, and 3 had low adult blood pressure levels observed in an earlier study of middle-aged men. Significant differences between the towns were found for the children's mean systolic blood pressure (range 96.7 to 102.4 mm Hg) and diastolic pressure (range 55.9 to 60.3 mm Hg). The pattern of systolic blood pressure differences in children was similar to that observed in the study of middle-aged men (r = 0.65). The town mean systolic pressures in children show an association with standardised mortality ratios for cardiovascular disease in adults. The pattern of geographical differences in blood pressure observed in British adult men may have its origins early in life.