BackgroundThere is no cumulative evidence supporting the role of coagulation indices in mortality among the critically ill patients with atrial fibrillation (AF).MethodsThe data were derived from the MIMIC-III database, which included a total of 2284 individuals. We explored the association between coagulation indices and mortality using multivariable correction analysis.Results2284 participants were included in the study with a median age of 71.29, and 1476 participants were male (64.62%). The median levels of coagulation indices -PTT, PT, INR PT and fibrinogen were 44.14 s, 16.95 s, 1.67 and 277.8 mg/dL, respectively. After adjusting for confounding factors, there were still strong positive correlations between coagulation indices and mortality (hospital mortality, 7-day mortality, 30-day mortality, and 1-year mortality), (all P < 0.001). In addition, stratified analysis showed that gender as a covariate affected the association between PTT and mortality; age, valvular disease, statins, heparin and aspirin were covariates that affected the association between fibrinogen and mortalityConclusionsOur study is the first to indicate that there is a positive correlation between coagulation indices (PTT, PT/INR PT, fibrinogen) and mortality in critically ill patients with AF.