BACKGROUND: Genetic and environmental factors are involved in the development of atrial fibrillation in arterial hypertension. This determines the relevance of studying gene-environment interactions in the occurrence of arrhythmia. AIM: To evaluate the contribution of the renin-angiotensin-aldosterone system genes polymorphisms to the susceptibility to atrial fibrillation in patients with arterial hypertension, and also to study the combined influence of these polymorphisms and environmental factors on the risk of arrhythmia. MATERIALS AND METHODS: The study included 60 patients with arterial hypertension and paroxysmal atrial fibrillation (study group), 60 patients with arterial hypertension without atrial fibrillation (comparison group-1) and 20 healthy volunteers (comparison group-2). Angiotensin-converting enzyme (ACE (I/D)) and angiotensin II type 1 receptor gene (AGTR1 (A1166C)) polymorphisms were analyzed by real-time polymerase chain reaction. RESULTS: Genotype II and allele I of the ACE gene (I/D) in patients with arterial hypertension and atrial fibrillation were significantly more frequent compared to patients with arterial hypertension without arrhythmia (χ² = 4.547; p = 0.03 and χ² = 4.818; p = 0.03 respectively). Carriage of genotype II in patients with arterial hypertension increased the chance of developing atrial fibrillation by 2.8 times (95% CI 1.19–7.18). The odds ratio (OR) for arrythmia development in patients with arterial hypertension and allele I was 1.8 (95% CI 1.10–3.07). The presence of obesity in patients with arterial hypertension in the presence of genotype II of the ACE gene (I/D) was associated with an increased risk of developing atrial fibrillation, compared with the genotype alone (OR = 4.16, 95% CI 1.16–19.87). A study of the A1166C polymorphism of the AGTR1 gene did not reveal a reliable significant relationship between its inheritance and the development of atrial fibrillation. CONCLUSION: Genotype II and allele I of the ACE gene (I/D) were statistically significantly more frequent in patients with arterial hypertension and atrial fibrillation. Carriage of genotype II and allele I of the ACE gene (I/D) increased the chance of developing atrial fibrillation in patients with arterial hypertension. Obesity had a significant effect on the susceptibility to atrial fibrillation in the presence of genotype II of the ACE gene (I/D) in hypertensive patients.