In connection with the Finnish Multicentre Study on the precursors of atherosclerosis in 3-, 6-, 9-, 12-, 15- and 18-year-old children and adolescents, blood pressure was measured in 3,596 subjects in the five university hospital areas. Blood pressure was measured with an ultrasound device (Arteriosonde 1020, Roche) in the 3-year-old children, and an ordinary mercury sphygmomanometer was used in the rest of the subjects. The systolic and diastolic values increased with age as has been shown earlier. There were no significant differences in the values between boys and girls except that the 15- and 18-year-old boys had values a little higher than girls of the same age. Weight and height correlated well to both systolic and diastolic blood pressures. Physical maturation also correlated to blood pressure.