This study evaluates the accuracy of Doppler echocardiography in estimating pulmonary artery pressure (PAP) and cardiac output (CO) in patients with pulmonary hypertension (PH). The study included 65 patients who underwent comprehensive Doppler echocardiography within 1 hour of right-heart catheterization. Using Bland-Altman analysis, the bias for echocardiographic estimates of PAP was −0.6 mm Hg, with 95% limits of agreement ranging from −38.8 to −40.0 mm Hg. Doppler echocardiography was inaccurate in 48% of cases, with underestimation being more common and often leading to misclassification of PH severity. For CO measurement, the bias was −0.1 L/min, with 95% limits of agreement ranging from +2.2 to −2.4 L/min. The study concludes that Doppler echocardiography may frequently be inaccurate in estimating PAP and CO in patients with PH, emphasizing the need for definitive hemodynamic assessment by right-heart catheterization.This study evaluates the accuracy of Doppler echocardiography in estimating pulmonary artery pressure (PAP) and cardiac output (CO) in patients with pulmonary hypertension (PH). The study included 65 patients who underwent comprehensive Doppler echocardiography within 1 hour of right-heart catheterization. Using Bland-Altman analysis, the bias for echocardiographic estimates of PAP was −0.6 mm Hg, with 95% limits of agreement ranging from −38.8 to −40.0 mm Hg. Doppler echocardiography was inaccurate in 48% of cases, with underestimation being more common and often leading to misclassification of PH severity. For CO measurement, the bias was −0.1 L/min, with 95% limits of agreement ranging from +2.2 to −2.4 L/min. The study concludes that Doppler echocardiography may frequently be inaccurate in estimating PAP and CO in patients with PH, emphasizing the need for definitive hemodynamic assessment by right-heart catheterization.