Atrial fibrillation (AF) progresses after coronary bypass grafting in 11–40% of patients. Plasma biomarkers such as interleukin 6 (IL-6) can assess the risk of AF development. We performed a systematic review using as sources: PubMed, LILACS, and Cochrane Library databases were investigated using Boolean operators and MeSH terms (Medical Subject Headings Terms) “Atrial Fibrillation AND Interleukin AND Biomarkers”. As the following eligibility criteria: observational studies, studies with coronary artery bypass grafting with plasma levels of IL-6 recorded after screening, 11 articles were selected. Three studies met the inclusion and exclusion criteria. Results: IL-6 levels on AF group - Ishida et al. reported the plasma levels of IL-6 during the post-operative period as 360 ± 143 pg/mL, while Pretorius et al. reported it to be 380.6 ± 151.1 pg/mL. Lastly, Ziabakhsh-Tabari et al. reported a post-operative plasma IL-6 level of 38.2 ± 32 pg/mL. It is considered that new studies about the object are necessary, and these studies should be more standardized. Preferably, it would be important for the daily measurement of IL-6 and its correlation with AF development for statistical analysis to set the best time for sample collection and cut-off value.