Introduction: Small animals, especially rats, are used in different experimental models of cardiovascular diseases, being often evaluated by echocardiography. However, there are little data about normal values, and also conflicting data regarding gender differences. Our aim was to assess left ventricular (LV) function by 2D standard and speckle tracking echocardiography (STE), in order to report gender differences in young adult Sprague-Dawley (SD) rats. Methods: 16 SD rats (21 ± 1 week, 8 male) were evaluated aft er general anesthesia with IM ketamine (100 mg/kg) and acepromazine (2 mg/kg). LV structure was assessed from the parasternal short-axis view by anterior (AWs, AWd) and posterior (PWs, PWd) systolic and diastolic walls thickness, and from the 4C apical view by end-diastolic and end-systolic LV volumes, while LV function by fractional shortening (FS) and ejection fraction (EF) by Teicholz formula; MAPSE, TEI index, and E/E’ were assessed from the apical views. Global circumferential (CS) and radial strain (RS) were assessed by STE, from the short-axis view. Cardiac output (CO) was calculated. All dimensions were indexed by body weight. Results: The weight was significantly different between females and males (271 ± 40 vs 342 ± 50 g, p < 0.01). There were no differences on FS (60 ± 8 vs 55 ± 4%), EF (92 ± 4 vs 89 ± 3%), MAPSE (1.98 ± 0.21 vs 2.04 ± 0.1 mm), TEI index (0.32 ± 0.14 vs 0.35 ± 0.08), E/E’ (19.3 ± 4.5 vs 17.6 ± 2.1), CS (-25 ± 4.7 vs -23 ± 2.7%), and RS (45 ± 6.8 vs. 50 ± 8.0%), and also not on indexed dimensions and volumes, which became signifi cantly diff erent (p < 0.01) when were indexed per body weight: AWs (10.6 ± 1.7 vs. 8.4 ± 0.9 mm/kg), AWd (6.2 ± 1.0 vs 4.7 ± 0.5 mm/kg), PWs (12.2 ± 1.5 vs 8.7 ± 0.9 mm/ kg), PWd (6.4 ± 0.9 vs 4.8 ± 0.6 mm/kg). CO (0.302 ± 0.05 vs 0.221 ± 0.03 ml/min/kg, p < 0.001) was higher in female rats, due to higher heart rate (383 ± 29 vs 322 ± 30 bpm, p < 0.001). Conclusions: Echo parameters of LV function, either systolic or diastolic, including LV deformation by STE, are similar between female and male SD normal rats, whereas indexed LV dimensions and volumes and cardiac output are diff erent. Our fi ndings should be taken into consideration in experimental cardiology models.