BACKGROUND: Previous studies on familial aggregation of blood pressure (BP) have reported data on family history of hypertension. Data on actual parental BP levels and the subsequent natural history of BP in their offspring are scarce. METHODS: In a population-based study with 596 children aged 5 to 19 years, cardiovascular risk factors were measured annually from 1975 through 2002. Parental data were obtained at baseline. Repeated BP measurements were studied as a function of tertiles of age-adjusted BP measured in their parents at baseline. RESULTS: Systolic BP during follow-up was higher in offspring whose parents were both in the highest tertile compared with children whose parents were not in the highest tertile (difference 2.7 mm Hg, 95% confidence interval 0.2 to 5.2). Having both parents in the highest tertile of diastolic BP resulted in a substantially higher diastolic BP ranging from 1.9 mm Hg at age 15 years to 8.5 mm Hg at age 45 years. These differences were adjusted for age, sex, body mass index, total serum cholesterol, smoking habits, and alcohol consumption. CONCLUSIONS: The results of this study indicate that actual parental BP is an important predictor of BP development from childhood into young adulthood. This is important when constituting cardiovascular risk profiles for children and young adults.