AIM: To investigate a balance between circulating regulatory T lymphocytes (Treg) exerting antiatherogenic activity and T helper type 1 (Th1) and T helper type 17 (Th17) cells having proatherogenic activity in patients with stable coronary artery disease (CAD) and different degrees of coronary atherosclerosis. MATERIAL AND METHODS: According to coronary angiography findings, 80 patients were allocated to 4 groups: 1) 18 patients with intact coronary arteries; 2) 21 with no progressive coronary atherosclerosis; 3) 16 with progressive coronary atherosclerosis (more than 50% stenosis) in the native coronary arteries; 4) 25 patients with three-vessel lesions. Groups 2 and 3 patients had undergone coronary stenting 23.8±8.4 and 22.4±8.7 months before their enrollment, respectively. Lymphocytes were typed by direct immunocytofluorometry: Treg was defined as CD4⁺CD25highCD127low and CD4⁺FoxP3⁺ lymphocytes. For CD4⁺IL-17a⁺ Th17 and CD4⁺INFgamma Th1 analysis, mononuclear cells were preactivated by culture. The serum levels of high-sensitivity C-reactive protein, IL-10, sCD25, and IL-17a were determined by nephelometry, chemiluminescence (Immulite) and ELISA, respectively. RESULTS: Group 4 was found to have lower Treg levels and higher Th17 levels than Group 1. The ratio of Th17/Treg proved to be higher in Groups 3 and 4 than in Group 1 and that of (Th1⁺Th17)/Treg was higher in Group 3 than in Group 2. The female patients had higher Tregs levels than the male ones. The Th17/Treg index turned out to be increased in patients with a history of myocardial infarction. CONCLUSION: The imbalance of pro- and anti-atherogenic lymphocyte subpopulations plays a role in the pathogenesis of CAD and is associated with progressive atherosclerosis.