Epicardial adipose tissue (EAT) is metabolically bioactive fat. The present study aimed to clarify the relationship between EAT amount and early impairment of left ventricular (LV) systolic function in patients with preserved ejection fraction (EF), all evaluated echocardiographically. Participants comprised 62 elderly women (mean age ± standard deviation, 68 ± 11 years) with lifestyle-related diseases and EF ≥ 60 %. EAT amount was evaluated as thickness. Parameters suggesting early impairment of systolic function such as decreases in systolic mitral annular velocity (S′) and tissue mitral annular displacement percentage (TMAD %) were evaluated along with EF. Correlations between EAT thickness and these LV systolic functions were assessed. Influences of various factors on the resultant significant relationships were also assessed. EAT thickness correlated inversely with S′ and TMAD % (r = −0.402, p = 0.001 and r = −0.585, p < 0.001, respectively), but did not correlate with EF (r = 0.054, not significant). These significant relationships were maintained after considering factors such as body mass index, age, presence of lifestyle-related diseases and blood test results. A significant relationship existed between EAT amount and early impairment of LV systolic function in patients with preserved EF. Accumulation of EAT might contribute to the initial development of LV systolic dysfunction.