Objective To explore the predictive value of D-dimer to fibrinogen ratio (DFR) for in-hospital death in patients with heatstroke.Methods The data of patients with heatstroke were analyzed retrospectively. According to the clinical outcome at discharge, the patients were divided into survival group and death group, and the clinical characteristics, treatment, test indicators and DFR of the two groups were compared. Multivariate Logistic regression was used to analyze the independent risk factors of death in hospital and ROC curve was used to evaluate its predictive value.Results The prothrombin time, activated partial thromboplastin time, D-dimer, DFR, the proportion of patients who needed to use booster drugs or input fresh frozen plasma was higher than that of the surviving group (P＜0.05), and systolic blood pressure and eGFR at admission were lower than that of the survival group (P＜0.05). Multivariate logistic regression analysis showed that DFR (OR=1.158, P＜0.05) was an independent risk factor for in-hospital death in patients with heatstroke. ROC curve showed that the AUC predicted by DFR for in-hospital death was 0.834, the optimum critical point was 3.38, the sensitivity was 75.0%, and the specificity was 81.8%. Conclusion DFR is an independent risk factor for in-hospital death in patients with heatstroke, and has high predictive value