Aim. To determine the blood level of inflammatory markers, parameters characterizing obesity and cardiac remodeling in patients with atrial fibrillation (AF) in combination with metabolic syndrome (MS).Material and methods. This single-stage case-control study included 677 subjects aged 35 to 65 years: patients with MS (n=407), of which 128 patients with AF; comparison group — patients with AF without MS (n=75); control group — practically healthy subjects without cardiovascular diseases and metabolic disorders (n=195).Results. It was found that the blood concentration of circulating pro-inflammatory biomarkers in patients with AF and MS is higher than in patients with AF without MS: C-reactive protein (CRP) (4,43 (2,68-4,98) and 2,33 (1,08-4,7) mg/L, p<0,0001), interleukin-6 (IL-6) (2,5 (1,28-5,13) and 1,27 (0,68-2,7) pg/ml, p<0,0001) and tumor necrosis factor-α (TNF-α) (5,18 (2,63-7,32) and 3,42 (2,115,48) pg/ml, p<0,0001). The serum CRP concentration positively correlates with left (ρ=0,451, p<0,0001) and right atrial (ρ=0,412, p<0,000) volumes, as well as with the waist circumference (ρ=0,503, p<0,001) and epicardial fat thickness (ρ=0,550, p<0,001). Plasma IL-6 and serum TNF-α levels correlated to a lesser extent with parameters characterizing atrial remodeling, but had a strong positive relationship with epicardial fat thickness. According to multivariate analysis, it was found that an increase in the epicardial fat thickness had a greater effect on an increase in blood concentration of CRP, IL-6 and TNF-α, in contrast to other parameters characterizing obesity, such as body mass index and waist circumference.Conclusion. An increase in the blood concentration of proinflammatory biomarkers CRP, IL-6, and TNF-α is associated with cardiac remodeling and epicardial fat thickness in patients with MS and probably has a pathogenetic role in increasing the AF risk in this cohort of patients.