A prospective echocardiographic and clinical study was performed on 84 Chinese patients with systemic lupus erythematosus (SLE) and 99 controls to investigate the prevalence and the mechanism of pulmonary hypertension (PH) in SLE. Comparison between Doppler estimation and catheterization measurement was made in 12 cases to validate the predictive method. Compared to normal subjects, lupus patients had significantly increased systolic pulmonary artery pressure (SPAP) (29.59 +/- 12.52 vs 19.64 +/- 5.82, P < 0.001), mean pulmonary artery pressure (MPAP) (15.11 +/- 7.36 vs 10.21 +/- 4.72, P < 0.001) and total pulmonary resistance (TPR) (315.85 +/- 190.65 vs 220.37 +/- 55.92, P < 0.001). Nine of the 84 patients presented PH, defined as SPAP < 30 mmHg and MPAP > 20 mmHg. Pulmonary hypertensive patients had higher serum endothelin (ET) than non-pulmonary hypertensive patients, were more commonly in active stages, and presented Raynaud's phenomenon and rheumatoid factors. ET level was correlated with echocardiographic pulmonary pressure. Pulmonary hypertension commonly occurs in Chinese patients with SLE (11%), and it correlates with the lupus activity and the elevation of serum endothelin.