The pathogenesis of atrial fibrillation (AF), the most common cardiac dysrhythmia, remains unknown. However, many recent studies point to an association between AF and inflammation because of a demonstrable significant correlation between the dysrhythmia and various biomarkers of inflammation. For example, C-reactive protein (CRP), a sensitive biomarker of systemic inflammation, has been reported to be significantly higher in patients with AF compared with a control group with no history of atrial dysrhythmias. Histological anomalies in the atria of patients with AF have also been observed. These anomalies may have an inflammatory basis, although it is not known if the structural changes within the atria of patients with AF are a cause or consequence of the dysrhythmia. Given the suggested involvement of inflammation with this dysrhythmia, an initiating factor for inflammation has been sought. Chronic bacterial infection is the most likely event to initiate and maintain an inflammatory process. Recently, bacteria infections have been hypothesized to be involved in the pathogenesis of AF, and Helicobacter pylori and Chlamydia pneumoniae are two bacteria that have aroused interest. Here, we give a brief overview of AF and then specifically explore the recent evidence that suggests that AF may be caused by bacterial infection(s) in certain patients.