Background: The intervention timing in atrial septal defect (ASD) or pulmonary valvular stenosis (PVS) is more dependent on symptoms than right ventricular (RV) damage in clinical practice. RV long-axis function is sensitive in revealing RV myocardial dysfunction. We evaluate the impact of different chronic loading conditions on RV long-axis function and its relationship to patients symptoms in ASD or PVS. Methods: Transthoracic echocardiography was performed in normals (n = 39) and patients with isolated secundum ASD (n = 45) or PVS (n = 38). RV volume- and pressure-overloading were defined as the ratio of RV/left ventricular end-diastolic dimension = 0.5 and RV systolic pressure = 40 mm Hg, respectively. RV long-axis dysfunction was defined as M-mode tricuspid annular plane systolic excursion (TAPSE) <1.6 cm. New York Heart Association (NYHA) functional class and other symptoms (decreased exercise tolerance, palpitation and chest pain) were recorded. Results: Thirty-nine (32.0 ) had normal loading (Group 1; 39 normals); 24 (19.6 ) had isolated volume-overloading (Group 2; all ASDs); 21 (17.2 ) had isolated pressure-overloading (Group 3; 21 PVSs) and 38 (31.1 ) had both overloading conditions (Group 4; 21 ASDs and 17 PVSs). RV long-axis dysfunction in abnormal loading groups were zero (0 , Group 2), 21 (100 , Group 3) and 22 (57.8 , Group 4) (?2 = 45.9, p <0.001). Group 3 were more symptomatic (NYHA functional class 2.5 ? 0.6 versus 1.6 ? 0.5, p <0.05) and had lower TAPSE (1.6 ? 0.4 versus 3.0 ? 0.7 cm, p <0.05) than Group 2. RV long-axis dysfunction was the strongest predictor of the presence of symptoms (odds ratio = 9.298, p <0.001). Conclusion: Chronic volume-overloading accentuates while pressure-overloading attenuates RV long-axis excursion and its impairment was associated with the presence of symptoms.