The renin-angiotensin system plays an important role in cardiovascular regulation. Abnormalities in genetic components of this system, such as the angiotensin-converting enzyme (ACE) gene, angiotensin II type 1 (AT1) receptor gene and angiotensinogen (AGT) gene, may cause a variety of adverse cardiovascular effects. It was the aim of this study, therefore, to investigate the involvement of the ACE insertion/deletion (I/D), AT1 receptor 1166 A->C and AGT M235T polymorphisms as predisposing factors for myocardial infarction (MI) in 195 young South African Indians (</= 45 years). Results were compared with those obtained I n 107 unaffected siblings (18-45 years old) and 300 healthy age- and race-matched control subjects. The distribution of the ACE genotypes was the same in each of the three study groups (p-value ranged between 0.83 and 0.98). No differences were observed in the 1166 A->C AT1 receptor polymorphism with respect to both genotype and allelotype (p > 0.70), or in the genotype or allele frequency distribution of the AGT M235T polymorphism (p > 0.44). However, a significant in crease was noted for both the AT1 receptor C variant (p = 0.025) and the AGT T variant (p = 0.047) in hypertensive patients compared with those who were normotensive. In conclusion, results of this study indicate that the ACE I/D, the 1166 A->C AT1 receptor and AGT M235T polymorphisms do not confer any increased risk for MI in young South African Indians.