Most measures that predict survival in pulmonary hypertension (PH) relate directly to, or correlate with, right ventricular (RV) function. Direct assessment of RV function using noninvasive techniques such as cardiac MRI may therefore be an appropriate way of determining response to therapy and monitoring disease progression in PH. In this pan-European study, 91 patients with PH (mean pulmonary arterial pressure 46±15 mm Hg) underwent clinical and cardiac MRI assessments at baseline and after 12 months of disease-targeted therapy (predominantly endothelin receptor antagonists 47.3% or phosphodiesterase type-5 inhibitors 25.3%). At month 12, functional class had improved in 21 patients, was unchanged in 63 patients, and had deteriorated in 7 patients. Significant improvements were achieved in RV and left ventricular ejection fraction (P<0.001 and P=0.0007, respectively), RV stroke volume index (P<0.0001), and left ventricular end-diastolic volume index (P=0.0015). Increases in 6-minute walk distance were significant (P<0.0001) and correlated with change in RV ejection fraction and left ventricular end-diastolic volume, although correlation coefficients were low (r=0.28, P=0.01 and r=0.26, P=0.02, respectively). On-treatment changes in cardiac MRI-derived variables from left and right sides of the heart reflected changes in functional class and survival in patients with PH. Direct measurement of RV function using cardiac MRI can fully assess potential benefits of treatment in PH.