INTRODUCTION: Short telomeres are often associated with cardiovascular risk factors and age-related diseases, while the angiotensin converting enzyme (ACE) gene insertion/deletion polymorphism (DD, ID, II) has shown such associations less consistently. We hypothesized that telomere length and association of telomere length with cardiovascular risk is affected by ACE (I/D) genotype. METHODS: We measured leucocyte telomere length (LTL) by Southern blot and analysed ACE I/D genotypes in 1249 subjects with hypertension and left ventricular hypertrophy (LVH). We examined interactions of ACE I/D genotype with LTL and cardiovascular risk. RESULTS: Mean LTL in DD or ID genotype was shorter (8.15 and 8.14 kb, respectively), than in II genotype (8.27 kb, p=0.0005). This difference was significant in the younger subjects (55-64 years, p=0.02) but not in the older group (65-80 years, p=0.56 ). In DD but not I/D or II genotype, proportion of short telomeres (