Studies on the right ventricular dysfunction (RV) in systemic lupus erythematosus (SLE) patients are limited, particularly in the pediatric age group. The study aimed to identify subclinical RV alterations in childhood-onset SLE (c-SLE) using conventional and three-dimensional echocardiography (3DE). Forty SLE pediatric patients and 40 healthy controls were included. Disease activity and chronicity were evaluated by SLE disease activity index (SLEDAI) score and SLE damage index (SDI). Participants underwent detailed RV echocardiographic examination with conventional and 3DE assessment using 3D auto RV software. Patients included 35/40 (87.5%) females with mean age of 15.6 ± 1.7 years. Using conventional pulmonary artery systolic pressure echocardiography-derived measurement, none of the c-SLE patients had pulmonary hypertension. By 3DE, RV end-systolic and end-diastolic volumes (p= < 0.001, 0.02, respectively) were greater, whereas 3D-derived RV ejection fraction (p< 0.001), septal, and lateral longitudinal strain (bothp< 0.001) were lower in SLE. SDI displayed a significant correlation with 3D auto RV ejection fraction (EF), tricuspid annular plane systolic excursion (TAPSE), fractional area change, and RV longitudinal strain (RVLS)-free wall (p= 0.01, 0.003, 0.007, and < 0.001, respectively). Cumulative SLEDAI score also showed a significant correlation with RV EF, TAPSE, FAC, and RVLS-free wall (p= 0.03, 0.007, 0.002, and < 0.001, respectively). By multivariate regression analysis, SDI remained an independent predictor of RVLS-free wall (ß coefficient − 0.4,p= 0.03) and TAPSE (ß − 0.5,p= 0.02).Conclusion: Subtle right ventricular myocardial dysfunction could be detected in childhood-onset SLE patients, especially via 3D-derived auto RV echocardiographic parameters, despite the absence of evident pulmonary hypertension. These parameters correlate with the SLE disease activity and chronicity scores.What is Known:•Diseases of the cardiovascular system are one of the most common causes of morbidity and mortality in SLE patients.•RV labeled the forgotten ventricle in many diseases, was also forgotten in SLE patients and has been rarely addressed in adults, with scarce research in pediatrics.What is New:•Right ventricular functions are affected in children with SLE in comparison to healthy controls, especially three-dimensional echocardiography-derived parameters, which is an aspect that has not been investigated in previous research in the pediatric age group.•Some of the detected myocardial dysfunctions of the right ventricle correlated with SLE disease activity and chronicity-related scores.