The insertion/deletion (I/D) polymorphism of the angiotensin converting enzyme (ACE) gene may be involved in determining blood pressure changes. The aim of the present study was to assess the relationship between the ACE I/D gene and the change of blood pressure levels during follow-up. We calculated the difference between mean levels of SBP, DBP and PP obtained during the two observations as follows: BP mean levels obtained at third phase minus the BP mean levels at baseline and subsequently we investigated the association of the ACE I/D polymorphism and the mean changes of SBP, DBP and PP levels. The study was conducted within the Rotterdam Study, a population-based cohort study including subjects aged 55 years and older. Information on the II, ID and DD genotypes of the ACE gene and mean change of blood pressure levels were available in 3966 subjects. In adjusted models, subjects with the D allele had higher mean changes of systolic and pulse pressure (PP) than subjects with the I allele. The mean changes of systolic blood pressure were 6.1 (4.7-7.5), 8.2 (7.5-9.3) and 7.4 (5.9-8.5) mm Hg in subjects with the II, ID and DD genotype, respectively. The corresponding mean changes of PP through genotypes were 4.3 (3.3-5.4), 6.0 (5.3-6.7) and 5.9 (4.9-6.9) mm Hg, respectively. No difference was found for mean change of diastolic blood pressure among genotypes. In conclusion, the results of this population-based study show that the ACE ID/DD genotypes are associated with increased mean changes of systolic and PP.