For the purposes of analyzing the distribution and the change in blood pressure according to age and determining the factors affecting the change in blood pressure, a follow-up study had been conducted for 6 years from 1986 to 1991 for 430 primary school children aged 6 years old in 1986 in Kangwha County, Korea. The mean blood pressure increased according to age. Specifically mean systolic blood pressure increased from 97.3 mmHg for male and 96.4mmHg for female (at 6 years of age) to 108.8mmHg fur male and 112.1mmHg for female (at 11 years of age). Mean diastolic blood pressure increased from 60.0mmHg for male and 61.8mmHg for female (at 6 years of age) to 72.9mmHg for male and 73.8mmHg for female (at 11 years of age). The average annual increase in blood pressure was 2.3mmHg (in systolic blood pressure) and 2.6 mmHg (in diastolic blood pressure) for male : and 3.1mmHg (in systolic blood pressure) and 2.4mmHg (in diastolic blood pressure) for female, respectively. To determine the factors affecting the change in blood pressure, the stepwise regression analysis was conducted. Children were divided into the three groups(low, middle, and upper) according to the level of systolic and diastolic blood pressure at the age of 6, and the regression analysis was performed in each group. For the change in systolic blood pressure, the changes in weight and skinfold thickness or initial skinfold thickness fer male, and the change in weight for female were selected as significant factors for children in middle and upper group. For the change of blood pressure in diastolic blood pressure, no variables was significant.