A longitudinal study of 251 children with primary hypertension (PH), aged 6-15 from Sofia, Bulgaria, was carried out over a 10-year period (1972-1983). The dynamics of blood pressure (BP), target organ changes, and risk-factors influence were followed up. In the tenth year, 44.2% of the persons remained hypertensive, 29.9% were found to be with borderline hypertension, and 25.9% with normal BP. Functional and structural changes in the heart were discovered in a considerable number of the persons by ECG, x-ray, and echocardiography examinations. Furthermore, angioretinopathy I and II gr. in 24.0%, hyperlipoproteinemia (IIA, IIB, and IV type) in 45.3% and low levels HDL-chol. (less than or equal to 0.905 mmol/l) in 34.5% were present at the end of the study in those young persons who had PH in childhood. A control group of 145 children with normal BP in 1972-1973 has been followed up over the same period.