lridology, a form of complementary and alternative medicine (CAM), is the diagnosis of medical conditions through noting irregularities of the pigmentation in the iris. lridological constitution has a strong familial aggregation and is implicated in heredity. Apolipoprotein E (apoE) gene polymorphism is one of the most well studied genetic markers of vascular disease. I investigated the relationship between iridological constitution and apoE polymorphism. I classified 87 hypertensive patients with family history of cerebral infarction and 79 controls according to iris constitution, and determined apoE genotype. Neurogenic type in hypertensives was 32.2% compared with 16.5% in controls (P<0.001). No differences in the apoE genotypes frequencies were observed in patients compared with those in controls ($x^2=0.726$, df-=2, P=0.696). However, in a population with ${varepsilon}3/{varepsilon}4$ genotype, the frequency of neurogenic constitution was significantly higher in hypertensives than in controls (60% vs. 0%) ($x^2=5.265$, df=l, P=0.022). These results could imply that apoE ${varepsilon}3/{varepsilon}4$ genotype and neurogenic iris constitution are risk factors for hypertension.