Abstract Aims Adipose tissue and inflammation may play a role in the pathophysiology of patients with heart failure (HF) with mildly reduced or preserved ejection fraction. We therefore investigated epicardial fat in patients with HF with preserved (HFpEF) and mid-range ejection fraction (HFmrEF), and related this to co-morbidities, plasma biomarkers and cardiac structure. Methods and results A total of 64 HF patients with left ventricular ejection fraction >40% and 20 controls underwent routine cardiac magnetic resonance examination. Epicardial fat volume was quantified on short-axis cine stacks covering the entire epicardium and was related to clinical correlates, biomarkers associated with inflammation and myocardial injury, and cardiac function and contractility on cardiac magnetic resonance. HF patients and controls were of comparable age, sex and body mass index. Total epicardial fat volume was significantly higher in HF patients compared to controls (107 mL/m2 vs. 77 mL/m2, P <0.0001). HF patients with atrial fibrillation and/or type 2 diabetes mellitus had more epicardial fat than HF patients without these co-morbidities (116 vs. 100 mL/m2, P =0.03, and 120 vs. 97 mL/m2, P =0.001, respectively). Creatine kinase-MB, troponin T and glycated haemoglobin in patients with HF were positively correlated with epicardial fat volume (R =0.37, P =0.006; R =0.35, P =0.01; and R =0.42, P =0.002, respectively). Conclusion Heart failure patients had more epicardial fat compared to controls, despite similar body mass index. Epicardial fat volume was associated with the presence of atrial fibrillation and type 2 diabetes mellitus and with biomarkers related to myocardial injury. The clinical implications of these findings are unclear, but warrant further investigation.