The effect of ACE (angiotensin-converting enzyme) and CYP11B2 (aldosterone synthase) gene polymorphism on the nitrites and nitrates total fraction content in blood plasma of healthy individuals and patients with arterial hypertension (AH) was studied. It was shown that the emergence of consistently high blood pressure is associated with a rise in the bloodstream nitric oxide level. Patients carrying the D/D genotype of the ACE gene polymorphic marker (rs4340) and without any AH clinical manifestations showed a significantly lower nitric oxide content compared to carriers of the I/I genotype (р = 0.028). Plasma NOx concentration was higher in hypertensive patients carrying the TT genotype in the -344T> C CYP11B2 gene polymorphic marker (rs1799998) than in individuals with the CC genotype (p = 0.037). We revealed the CYP11B2 gene polymorphism (rs1799998) effects on the blood plasma nitrite and nitrate content (F = 3.39; p = 0.037). Our results indicate the involvement of ACE and CYP11B2 gene polymorphism in the nitric oxide level regulation during hypertension development.