Background: Several studies have reported the accuracy and reproducibility of HeartModel for automated determination of three-dimensional echocardiography (3DE)-derived left heart volumes and left ventricular (LV) ejection fraction (LVEF) in adult patients. However, it remains unclear whether this automated adaptive analytics algorithm, derived from a 'training' population, can encompass adequate echo images in Chinese adolescents. Objectives: The aim of our study was to explore the accuracy of HeartModel in adolescents compared with expert manual three-dimensional (3D) echocardiography. Methods: Fifty-three Chinese adolescent subjects with or without heart disease underwent 3D echocardiographic imaging with an EPIQ system (Philips). 3D cardiac volumes and LVEF obtained with the automated HeartModel program were compared with manual 3D echocardiographic measurements by an experienced echocardiographer. Results: There was strong correlation between HeartModel and expert manual 3DE measurements (r = 0.875-0.965, all P < 0.001). Automated LV and left atrial (LA) volumes were slightly overestimated when compared to expert manual measurements, while LVEF showed no significant differences from the manual method. Importantly, the intra-and inter-observer variability of automated 3D echocardiographic model was relatively low (<1%), surpassing the manual approach (3.5-17.4%), yet requiring significantly less analyzing time (20 +/- 7 vs 177 +/- 30 s, P < 0.001). Conclusion: Simultaneous quantification of left heart volumes and LVEF with the automated HeartModel program is rapid, accurate and reproducible in Chinese adolescent cohort. Therefore, it has a potential to bring 3D echocardiographic assessment of left heart chamber volumes and function into busy pediatric practice.