Introduction: Atrial fibrillation (AF) is a prevalent heart arrhythmia in elderly adults aged 80 years or older. The red cell distribution width to albumin ratio has been acknowledged as a reliable prognostic marker for poor outcomes in a variety of disorders. However, there exists limited scientific evidence on the association of red cell distribution width to albumin (RAR) with mortality in geriatric individuals with AF.Methods: From January 2015 to June 2020, a retrospective study was conducted in a tertiary academic institution that diagnosed 1141 elderly adults with atrial fibrillation (AF). The RAR value was calculated as the ratio of RDW (%) to albumin (g/dL). The potential association between RAR and cardiovascular mortality and the risk of all-cause mortality within 28 days was evaluated by means of multivariable Cox regression analysis.Results: The 28-day all-cause and cardiovascular mortality rates were 8.7% and 3.3%, respectively. Increased RAR tertiles were found to be significantly associated with greater all-cause mortality (T1: 1.6%; T2: 6.2%; T3: 18.1%, P < 0.001) and cardiovascular mortality (T1: 0.8%; T2: 2.9%; T3: 6.3%, P < 0.001) using Kaplan-Meier analysis. Continuous RAR had a positive association with all-cause mortality (HR=1.42, 95% CI 1.23-1.65) and cardiovascular mortality (HR=1.31, 95% CI 1.05-1.64), even after accounting for numerous confounding variables. In comparison to the T1 group, individuals with the highest RAR levels displayed a greater risk of all-cause mortality (HR=2.73, 95% CI 1.11-6.74) and cardiovascular mortality (HR=2.59, 95% CI 0.69-9.78). Increased RAR levels were related to higher rates of cardiovascular and all-cause mortality across almost all subgroups. Conclusion: RAR is independently correlated with 28-day all-cause mortality and cardiovascular mortality in AF-affected individuals aged >= 80. Keywords: cardiovascular disease; mortality; older; red cell distribution width; atrial fibrillation