The deletion polymorphism, situated in intron 16, of angiotensin-converting enzyme (ACE) gene (17q23) has been observed to be associated with an increased risk for myocardial infarction and left ventricular hypertrophy in Caucasian populations. The homozygous genotype for the deletion allele (DD) has additionally been observed at greater frequencies in hypertensive individuals of African-American and Japanese origin. In a population-based study of a Sikh population, we compared the occurrence of the insertion/deletion polymorphism at the ACE gene in subjects with hypertension to those with normal blood pressure. The ACE deletion allele was observed with a greater frequency in hypertensive subjects than in the normotensive subjects (p < 0.0001). These findings raise the possibility that in some ethnic subgroups, variation in or near the ACE gene may contribute to the development, and severity, of hypertension.