The clinical significance of the apolipoprotein E genotype in patients with hypertension has been a subject of debate. We enrolled 94 patients with hypertension and 102 healthy controls in this study and determined their plasma levels of triglyceride, total cholesterol, high- and low-density lipoprotein-cholesterol, apolipoprotein AI, and apolipoprotein B. The apolipoprotein E genotypes were identified by polymerase chain reaction, restriction fragment length polymorphism, and polyacrylamide gel electrophoresis. Apolipoprotein E3/4 genotype and set membership, vertical bar on horizontal stroke 4 allele frequencies in the hypertensive group were higher than in controls. In hypertensive patients with apolipoprotein E3/4 and E4/4 genotypes, systolic blood pressure was significantly higher than in those with apolipoprotein E2/3 or E3/3 genotypes. Meanwhile, the plasma levels of total cholesterol, low-density lipoprotein-cholesterol, and apolipoprotein B were higher in hypertensive patients with the.4 allele than the set membership, vertical bar on horizontal stroke 2 or set membership, vertical bar on horizontal stroke 3 allele. The echographic measurements of carotid artery intimal-medial thickness showed increasing values from set membership, vertical bar on horizontal stroke 2 to set membership, vertical bar on horizontal stroke 4 allele carriers in the hypertensive group. Analysis of variance showed that the carotid intimal-medial thickness was significantly greater in hypertensive patients with set membership, vertical bar on horizontal stroke 4 alleles compared with set membership, vertical bar on horizontal stroke 2 or set membership, vertical bar on horizontal stroke 3 alleles. Our data show an association between apolipoprotein E genotype and hypertension and support the hypothesis that the apolipoprotein set membership, vertical bar on horizontal stroke 4 allele is a susceptibility locus for systolic hypertension and carotid artery atherosclerosis.