The studies on the association of deletion/insertion (D/I) polymorphism of angiotensin converting enzyme (ACE) gene with blood pressure and hypertension reported contradictory results. We review the articles that considered blood pressure or hypertension as the main outcome measure to have an overview of the situation. There is heterogeneity of allele frequencies of ACE locus among ethnic groups. In descending order of D allele frequencies, ethnic groups are: Gulf Bedouin (0.657), Black (0.597), White (0.577), Chinese (0.400), Japanese (0.377), Bangladeshi (0.374) and Indian Sikh (0.373). Multiple studies were available for the Caucasians and Japanese with relatively large sample sizes. Three out of five studies in the Caucasians found association either in males or in females with blood pressure or hypertension. None of the three Japanese studies observed an association. So, ACE locus may be considered a marker for blood pressure or hypertension in the Caucasians but not in the Japanese. This racial difference is not surprising, because heterogenecity of ACE activity according to ACE genotypes has been reported among ethnic groups, and important differences in environmental factors persist. Studies in other populations were either small or sampling procedures were not adequately described. Given that the studies varied in designs, settings, sample size, and adjustment for confounding variables, adequately powered large-scale multicentre, multi-ethnic population-based studies using same method are required to resolve this contradiction.