Cardiopulmonary hemodynamics are estimated by Doppler echocardiogram (ECHO) and measured by right heart catheterization (RHC) in patients with pulmonary arterial hypertension (PAH). Whether there is a correlation between these measurements is controversial. The authors investigated ECHO and RHC in patients enrolled in the Registry to Evaluate Early and Long-Term PAH Disease Management (REVEAL), a multicenter, observational, US-based study designed to provide current information about patients with PAH. Patients with PAH who had an ECHO and RHC within 12 months of each other were included. Correlation between subsequent ECHO and RHC was also investigated. Of 2967 patients, 2838 were 18 years and older at enrollment and 1883 had an RHC within 12 months of an ECHO. Correlations between ECHO-estimated and RHC-measured pulmonary artery systolic pressures (PASPs) and mean right atrial pressures did not change based on temporal proximity of the two baseline studies, whether they occurred on the same day or were separated by up to 12 months. In contrast, there was little correlation of serial measurements between ECHO and RHC. Although there is good correlation in PASP between ECHO and RHC at baseline, repeat ECHO measurements alone are not sufficient to monitor change in PASP or progression of PAH.