Heart morphology and function may be non-invasively evaluated by ultrasonography. Rodent models have been used to study several diseases. This study aimed to describe the technique for the evaluation of rats’ heart by ultrasonography. The animals should be anesthetized by an intraperitoneal injection of ketamine (37,5 mg/kg) and xylazine (5 mg/kg) and the left region of the thoracic wall should be shaved using a machine clipper. The animals should be placed in left lateral recumbency and ultrasound transmission gel applied in the left thoracic wall. We have used the Logiq P6 apparatus and a high frequency linear probe (10-12 MHz). Parasternal long-axis (LAX), parasternal short-axis (PAS), 4-chamber view and suprasternal views are obtained, using Bmode, M-mode, Power Doppler, and Pulsed Doppler. The images can be recorded in the ultrasound apparatus, and then exported and analysed using Horos, or a similar software. In the LAX images may evaluated the following parameters: diastolic interventricular septal thickness (IVS d), diastolic left ventricular lumen (LV d), diastolic left ventricular posterior wall thickness (LVPW d), systolic interventricular septal thickness (IVS s), left ventricular lumen in systole (LV s), left ventricular posterior wall thickness in systole (LVPW s) and aorta artery diameter (Ao d). Heart rate (HR) and pulmonary artery dimeter (Pa d) can be evaluated in LAX images. In the 4-chamber images can be evaluated the following parameters: left atrial area (LA), right atrial area (AD), tricuspid annulus plane systolic excursion (TAPSE), and E/A wave ratio. Additionally, left ventricular ejection time (LVET) can be evaluated in the suprasternal view.