A negative correlation between birth weight and subsequent blood pressure has been reported, but in some studies this correlation has not been found. We analyzed the effect of birth weight and pubertal development and several pre- and postnatal factors on subsequent blood pressure among 2500 children and adolescents in a follow-up study with three surveys conducted with 3-y intervals. The correlations between birth weight and systolic blood pressure varied from -0.04 to 0.02 among the female subjects and from -0.05 to -0.04 among the male subjects in each survey. A somewhat stronger relation was found among the postpubertal female and male subjects (correlation coefficient -0.09 and -0.05) in the last survey. When adjusted for weight, the correlations became negative and more often significant. The decrease in the adjusted mean systolic blood pressure was about 2 mm Hg when birth weight increased from the lowest to the highest tertile. Other factors affecting systolic blood pressure were current age (mean change up to 1.8 mm Hg/ y) and weight (mean change up to 1.2 mm Hg/kg), the duration of breast feeding over 3 mo (mean change up to -6.5 mm Hg), and a birth rank order over four (mean change up to 5.0 mm Hg) presented as the mean difference from the baseline. According to the multiple regression analysis, a history of mother's high blood pressure during pregnancy (p < 0.05) predicted future blood pressure more eminently than birth weight. In conclusion, our results based on healthy children and adolescents offer support for the theory of low birth weight as a predicting factor for future blood pressure. However, other pre- and postnatal factors seem to be important as well.