Cardiac structural and functional abnormalities are observed in metabolic syndrome. However, such changes have not been investigated in the SHRSP.Z-Lepr(fa)/IzmDmcr rat (SHRSP-fatty) model of metabolic syndrome. Here we compare cardiac size and hemodynamic function in these rats with their lean littermates (SHRSP) and normotensive control Wistar-Kyoto rats (WKY). In male 16-week-old SHRSP-fatty, we determined heart rate and systolic blood pressure (SBP) by tail-cuff, cardiac output (CO), subcutaneous peripheral blood flow (BF) and stroke volume (SV) by plethysmography, and systolic and diastolic functions by echocardiography. We also assessed weight and collagen type I expression by Western blot in isolated atrium and ventricle, and beat rate in isolated atrial preparation by myography. Heart rate was lower in conscious SHRSP-fatty than SHRSP, and the beat rate of isolated atria was lower in SHRSP-fatty and SHRSP than that of WKY. Atrial weight was larger in SHRSP-fatty than others. Ventricular weight of SHRSP-fatty and SHRSP was larger than WKY. There were significant inverse correlations between atrial weight and heart rate or beat rate in SHRSP-fatty. SBP, CO, BF and SV were increased in SHRSP-fatty similarly to SHRSP. Increased deceleration time and decreased E/A ratio, and preserved fractional shortening were observed in SHRSP-fatty. Expressions of collagen type I were increased in atria and ventricle of SHRSP-fatty. SHRSP-fatty with metabolic syndrome exhibit cardiac changes, including slowed heart rate, ventricular diastolic dysfunction, and fibrosis, and atrial enlargement. SHRSP-fatty may be a useful rat model to study on cardiac abnormalities in metabolic syndrome.