The data describing the change in exercise capacity after surgical or interventional management of the patient with right ventricular (RV) outflow tract (OT) dysfunction are conflicting. The pathophysiologic consequences of RVOT interventions and the subsequent change in exercise performance are still poorly understood. We sought to assess the effect of percutaneous pulmonary valve implantation (PPVI) on exercise capacity in (1) patients with predominantly pulmonary stenosis (PS) and (2) in patients with predominantly pulmonary regurgitation (PR). A total of 63 patients with either predominantly PS (n = 37) or PR (n = 26) underwent PPVI. Cardiopulmonary exercise testing and magnetic resonance imaging were performed before and within 1 month after PPVI. On magnetic resonance imaging, the at rest effective biventricular stroke volumes improved in both groups after PPVI (p <0.001), but the ejection fraction improved only in the PS group. In the PS group, exercise capacity (peak oxygen uptake, p <0.001), ventilatory efficiency (p <0.001), and peak oxygen pulse (p <0.001) improved after PPVI. In the PR group, none of these parameters changed after PPVI (p = 0.6, p = 0.12, and p = 0.9, respectively). On multivariate analysis, the reduction in RVOT gradient was the only predictor of improved peak oxygen uptake when assessed in the whole patient group (r_part = −0.59; p <0.001) or in the PS (r_part = −0.45; p = 0.002) or PR groups alone (r_part = −0.45; p = 0.02). In conclusion, acutely after PPVI, exercise capacity improves with the relief of stenosis but not regurgitation. A reduction in the RVOT gradient, even small gradients, was the only independent predictor of improved peak oxygen uptake in both patient groups, irrespective of improved pulmonary valve competence.