Background: Echocardiography is used in humans to characterise the structure and function of the heart, yet is relatively uncommon in studies on the rat, the most commonly used model of human cardiovascular disease. The aim of this study was to show that echocardiography in rats provides useful information on cardiac changes occurring in thyroid dysfunction and can also be used to characterise cardiac abnormalities. Methods: Transthoracic echocardiography and Doppler techniques with high frequency, high frame rate imaging were used to define cardiac dimensions and function in 240 Wistar rats and cardiac abnormalities in Wistar and spontaneously hypertensive rats (SHR). Results: Echocardiographic assessment of left ventricular dimensions and function and aortic flows was technically feasible in almost all adult Wistar rats and SHR, including those with thyroid dysfunction and cardiac abnormalities. Pulsed-wave Doppler profiles of mitral inflows to estimate diastolic function were less reliably obtained. Conclusions: Echocardiography is a powerful technique for non-invasive and serial determination of cardiac structure and function in rat models of human cardiovascular disease.