In many cases, atrial fibrillation (AF) is associated with a history of cardiac inflammation. One of the potential pathogens responsible for atrial inflammation might be Borrelia burgdorferi – a pathogen involved in Lyme carditis. This study aimed to assess whether the serological history of Borrelia infection was associated with the risk of AF. The study included 113 AF patients and 109 patients in sinus rhythm. All patients underwent a clinical evaluation, echocardiography and had their blood taken for the assessment of anti-Borrelia IgG antibodies. Patients with AF compared with the non-AF group had more often serological signs of Borrelia infection (34.5% vs 6.4%; p <0.0001). The multivariate analysis showed that positive results for anti-Borrelia IgG antibodies were a strong independent predictor of AF (odds ratio 8.21; 95% confidence interval 3.08 to 21.88; p < 0.0001). In conclusion, presented data show that exposure to Borrelia spp. infection is associated with an increased risk of AF. Whether the early treatment of Lyme disease lowers the risk of AF development remains to be explored.