Right ventricular function is a major determinant of symptomatology and prognosis in severe pulmonary hypertension. The diagnosis of right heart failure rests on a clinical approach with invasive and noninvasive measurements. Magnetic resonance and echocardiographic imaging of the right ventricle is of prognostic relevance. The gold standard of right ventricular function is the ratio of end-systolic to arterial elastances determined from synchronized volume and pressure measurements. Pressure measurements can be obtained during a right heart catheterization and volume measurements by integration of Doppler pulmonary flow-velocity, magnetic resonance imaging, or, more recently, three-dimensional echocardiography. Imaging also informs about regional function and derived estimates of dyssynchrony and asynchrony. Modern imaging with 3D echocardiography and magnetic resonance aims at improved assessment of regional function and right ventriculo-arterial coupling to assist in the evaluation and prognostication of severe pulmonary hypertension.