The aim of this report was to estimate the risk of hypertension in children with primary vesicoureteral reflux (VUR). Between 1970 and 2004, 735 patients were diagnosed with VUR at a single tertiary renal unit. Of 735 patients, 664 (90%) were systematically followed and had multiple measurements of blood pressure. Hypertension was defined as values persistently above 95th for age, sex, and height in three consecutive visits. Risk of hypertension was analyzed by the Kaplan-Meier method. Of 664 patients followed, 20 (3%) developed hypertension. The estimated probability of hypertension was 2% (95%CI, 0.5%-3%), 6% (95%CI, 2%-10%), 15% (95%CI, 11%-20%) at 10, 15, and 21 years of age, respectively. The prevalence of hypertension has increased with age: it was 1.7% for patients with 1 yr-9.9 yr, 1.8% for adolescents with 10 yr-14.9 yr, 4.7% for patients with 15-19.9 yr, and 35% for patients>20 years at the end of the follow-up (P<0.001). It was estimated by survival analysis that 50% of patients with unilateral and bilateral renal damage would have sustained hypertension at about 30 and 22 years of age, respectively. Hypertension increased with age and was strongly associated with renal damage at entry in an unselected population of primary VUR.