Background: Echocardiographic measurements are widely used as outcomes of different studies. The aim of this study was to assess intraobserver and interobserver reliability of echocardiographic measurements in healthy children. Materials and methods: We studied 28 children, with a median age of 7.5 years, and inter-quartile range from 3 to 11 years. Intraobserver and interobserver reliability were assessed by repeated measurements of the diameters of the aortic root, the left atrium, and left ventricular end-diastolic structure. We also measured the ventricular end-diastolic septal thickness and the end-diastolic thickness of the left ventricular posterior wall. We calculated intraclass correlation coefficients, with corresponding 95% confidence intervals, and computed Bland and Altman plots, permitting us to derive limits of agreement plus or minus 2 standard deviations for the mean differences in cardiac measurements. Results: We found high intraobserver and interobserver intraclass correlation coefficient, ranging from 0.91 for ventricular septal thickness, with 9596 confidence intervals from 0.78 to 0.96, to 0.99 for the diameter of the aortic root, 95%, confidence interval from 0.97 to 1.00. Limits of agreement in the Bland and Altman plots ranged from zero millimetres for left ventricular end-diastolic posterior wall thickness to 1.60 millimeters (6.396) for left atrial diameter. Conclusions: Our study demonstrated good repeatability and reproducibility for ultrasonic measurements of left cardiac structures in children, showing that values obtained for measurement of these structures in both clinical and epidemiological research projects can be confidently accepted.