Background: The reduction of right ventricular function after heart valve surgery was associated with mortality and morbidity after cardiac surgery, prolonged ICU length of stay, and higher hospital cost. Inspiratory muscle training can be considered for improving right ventricular systolic function by optimizing afterload dan cardiac contractility. The study aims to determine the effect of inspiratory muscle training on right ventricular systolic function in patients after heart valve surgery.Methods: Patients undergoing heart valve surgery were randomized into a conventional preoperative rehabilitation group and conventional preoperative rehabilitation added high-intensity inspiratory muscle training at least 14 days before surgery. Echocardiography examination was performed before rehabilitation and after cardiac surgery.Results: There were 24 subjects consist of 12 control group and 12 intervention group. By using independent t-test or Mann Whitney test, we found significant differences on right ventricular function between intervention and control group, by using RV free wall strain (17.7 + 3.0% and 14.4 + 4.0%; p=0.033), RV FAC (43.2 + 4.9% and 35.1 + 8.8%; p=0.006), and TAPSE (12.7 + 3.4 mm and 9.9 + 2.7 mm; p=0.039). ICU length of stay in the intervention group was significantly shorter than the control group (3.2 + 0.8 and 4.2 + 1.3 days; p=0.044).Conclusion: Patients underwent conventional preoperative rehabilitation added inspiratory muscle training had better right ventricular systolic function than patients in control group.