In patients with acquired or congenital heart diseases, the systolic pulmonary artery pressure (PAPs) can be predicted using continuous-wave Doppler ultrasound (CWD) measurement of the peak velocity of a tricuspid regurgitation (TR) jet. The aim of this study was to determine whether CWD could be used to accurately estimate PAP in patients with chronic obstructive pulmonary disease (COPD). In 41 patients with stable COPD, we prospectively performed CWD and right heart catheterization. The mean value of PAPs for the entire group was 38.5 +/- 14.9 mm Hg. Pulmonary arterial hypertension (PAPs greater than or equal to 35 mm Hg) occurred in 51 percent (21/41) of patients. Doppler estimation of PAP was impossible in 34 percent (14/41) because of poor signal quality (n = 3), absence of Doppler-detected TR (n = 8), and inadequate TR Doppler signal (n = 3). The PAP could be estimated in 66 percent (27/41) of patients. A statistically significant correlation was found between the Doppler-estimated PAP and the catheter-measured PAPs (r = 0.65; p less than 0.001; SEE = 9 mm Hg). Therefore, CWD appears to be useful for the noninvasive estimation of PAP in patients with COPD. However, this method is associated with two limitations: (1) the high percentage of patients in whom the PAP cannot be estimated by CWD, mainly because of the absence of Doppler-detected TR, and (2) the high value of the standard error of the estimate. The combination of CWD with other Doppler methods should increase the feasibility and accuracy of Doppler echography for the prediction of PAP in patients with COPD.