OBJECTIVES: This study aimed to examine the association of adipocyte fatty acid-binding protein (FABP4) levels with left ventricular diastolic dysfunction (LVDD) in obese subjects with varying degrees of the metabolic syndrome (MetS). METHODS: Fifty morbidly obese subjects with LVDD were selected at random and matched by age (+/- 5 years) and sex with 50 morbidly obese with normal left ventricular (LV) function. In addition, 24 healthy lean subjects were included as controls. RESULTS: Median FABP4 levels (interquartile range) in obese subjects with LVDD were significantly higher (42 ng ml(-1) (32-53)) than in obese with normal LV function (24 ng ml(-1) (36-43), P = 0.036), and in normal weight controls (13 ng ml(-1) (10-20), P<0.0001). Increasing FABP4 tertiles were significantly associated with parameters of LVDD, the number of LVDD components, physical performance and epicardial fat thickness. In multivariate regression analysis adjusting for age, sex and adiposity, FABP4 levels remained significantly associated with parameters of diastolic function. The association of FABP4 levels with LVDD was mainly observed in subjects with metabolic complications, but not in metabolically healthy obese. CONCLUSIONS: FABP4 levels are significantly associated with LVDD in obese subjects, when the MetS is present. Thus, FABP4 may be a link between obesity and cardiometabolic disorders.