Heart failure with a normal ejection fraction (HFNEF) is common in obesity and coronary artery disease (CAD). Both ischemia and reperfusion induce leptin (LEP) and leptin receptor (LEPR) gene expression. We aimed to investigate the possible associations of serum leptin, leptin gene and leptin receptor gene polymorphism with HFNEF in patients with CAD. 100 Egyptian CAD patients with HFNEF and 100 healthy subjects (the control group) were genotyped for LEP and LEPR polymorphism. Leptin levels were measured. Serum leptin levels were significantly increased in patients compared to the control group. There was a significant increase in the leptin gene (AA genotype) and the leptin receptor gene (RR genotype) in HFNEF patients compared to the control group. Leptin levels, leptin gene (AA genotype) and LEPR (RR genotype) were more associated with NYHA III than with NYHA I and II. We thus concluded that HFNEF is associated with increased serum leptin levels, and the LEP AA genotype or LEPR RR genotype carries at least a threefold increased risk of developing HFNEF.