Introduction: Sprague-Dawley (SD) and Wistar (W) rats are the two most frequently used rat strains in cardiovascular experimental models. SD strain is derived from W, both being outbred albino strains. It is presumed that echocardiographic parameters are similar but, currently, there is no detailed study to compare them using standard, tissue Doppler, and speckle tracking echocardiography (STE). Methods: 20 male rats (10 SD), age-matched (24 ± 4 weeks), were evaluated after IM anesthesia (ketamine 100mg/kg + acepromazine 2 mg/kg). LV structure was assessed from the SAX view by anterior (AWS, AWD) and posterior (PWS, PWD) walls thickness and LV diameters at end-diastole and end-systole, while LV function by fractional shortening (FS) and ejection fraction (EF) (Teicholz formula); MAPSE, TEI index, septal mitral annular systolic velocity (S’VS), and E/E’ were assessed from the apical views. Global circumferential (CS) and radial strain (RS) were assessed by STE, from the SAX view at the level of papillary muscle. Right ventricle (RV) was assessed from transversal diameter, TAPSE and S’RV. LV mass and cardiac output (CO) were calculated. All dimensions were indexed by body weight. Results: SD strain had higher body weight (346 ± 45 vs. 295 ± 51 g, p < 0.03), lower heart rate (328 ± 34 vs. 400 ± 68 bpm, p = 0.008) and thinner LV walls (AWS 8.3 ± 0.9 vs. 9.9 ±1.6 mm/kg; PWS 8.5 ± 0.9 vs. 10 ± 1.3 mm/ kg; both p < 0.01) than W strain. LV diameters (endsystole: 7.49 ± 2.48 vs. 8.20 ± 2.09 mm/kg), FS (54 ± 4 vs. 58 ± 7%), EF (89 ± 3 vs. 91 ± 5%), MAPSE (1.99 ± 0.3 vs. 1.81 ± 0.5 mm), TEI index (0.32 ± 0.12 vs. 0.30 ± 0.10), S’VS (5 ± 1 vs. 5 ± 1 cm/s), E/E’ (18 ± 2 vs. 22 ± 11), and LV strain (CS: -23 ± 2 vs. -24 ± 3 % and RS: 49 ± 8 vs. 46 ± 8 %) were similar, as well as parameters of RV structure (diameter: 10.42 ± 1.26 vs. 11.18 ± 1.30 mm/kg) and function (S’RV: 6 ± 1 vs. 6 ± 1 cm/s), LV mass (1.77 ± 0.3 vs. 1.82 ± 0.3 mg/g) and CO (238 ± 48 vs. 270 ± 60 ml/min/g); all p > 0.05. Conclusions: There were only minor differences in LV wall thickness between SD and W male rats, whereas more detailed parameters of LV and RV structure and function are similar. Th erefore, we suggest these two strains could be used as homogeneous group in cardiovascular experimental models.