The aim of the study was to analyze changes of systolic and diastolic blood pressure values over five and ten years separately boys and girls and to estimate correlation between them. Three age groups from 8 centers in Serbia were evaluated: Group 1: 10 year old patients, Group 2: 15 year old and Group 3: 20 year old. Group with normal blood pressure values, prehypertensive and hypertensive group were analyzed. Regarding the period of follow-up we analyzed: 10/15 years period-children between 10 and 15 years, 15/20 years period-children between 15 and 20 years, and 10/20 years period-children between 10 and 20 years. Significant increase of diastolic blood pressure was noticed for both genders in 10/15 years period of prehypertensive population, while in hypertensive children, boys showed decline in frequency for systolic and diastolic blood pressure and girls only for diastolic. In 15/20 years period there was significant decrease of prehypertensive and significant increase of hypertensive diastolic blood pressure frequency. In 10/20 years period significant reduction in frequency of prehypertensive systolic blood pressure was noticed, while only hypertensive group of boys showed significant reduction regarding systolic blood pressure frequency. Prehypertensive diastolic and hypertensive systolic blood pressure fluctuations are more related to age.