Background Left ventricular (LV) ejection fraction (LVEF) assessed by two-dimensional echocardiography (2DE) is the most widely used parameter for clinical decision-making, but reproducibility and accuracy problems remain. We evaluated the usefulness of a novel training program based on cardiac magnetic resonance (CMR) imaging to obtain more reliable values of 2DE-derived LVEF and LV volumes. Methods Fifty-four sonographers from five hospitals independently measured LV volumes and LVEF using the same 2DE images from 15 patients who underwent CMR and 2DE. After receiving a lecture from an expert on how to properly trace the LV endocardium, each sonographer voluntary performed the measurements using the same datasets, and was invited to perform the same analysis for additional patients. The effect of the training intervention was evaluated using the coefficient of variation (CV) and coverage probability (CP). Results Before the intervention, the LV volumes were significantly underestimated and the LVEF was significantly overestimated compared to the CMR results; however, these differences were reduced after the intervention. In particular, the CP (0.52 vs. 0.76, p Conclusions A training program using CMR as a reference improved the accuracy of 2DE-determined LV measurements. Since the degree of improvements differed among hospitals, individualization of training programs and periodical objective evaluation may be required to reduce inter-institutional variability.