Pulmonary arterial hypertension (PAH) is the major complication of systemic sclerosis (SSc) and the main cause of morbi-mortality. It is important to find predictors for this vascular problem. The objective of this study was to determine the serum levels of different biomarkers in patients with SSc and secondary PAH and to compare them with those of healthy control subjects to define their potential role as predictors of PAH. Cross-section study in which 20 patients with SSc were included. PAH was diagnosed by echocardiogram. The optical densities of endoglin (Eng), endothelin-1 (ET-1), platelet-derived growth factor (PDGF), tumoral necrosis factor alpha (TNF-alpha), Transforming growth factor beta 2 (TGF-beta2) and Interleukin 8 (IL-8) were measured in 20 patients with SSc and 20 healthy controls matched by sex. The differences found between the group of patients with PAH and the control group were (mean or median and range): ET-1 (0.20; 0.10-0.35 vs. 0.16; 0.10-0.24; P = 0.0276), IL-8 (195.7; 45.5-504 vs. 118.9; 23-299.5; P = 0.0364), TNF-alpha (0.70; 0.50-0.96 vs. 0.48; 0.38-0.65; P = 1 x 10(-8)) and Eng (0.95; 0.57-1.72 vs. 0.75; 0.57-0.89; P = 0.0028). A correlation was found between the progression of the disease and the development of Raynaud's phenomenon (Rho: 0.67 and P = 0.0011), ET-1 and Eng (Rho: 0.53 and P = 0.0196), and between IL-8 and Eng (Rho: 0.68 and P = 0.0019). In conclusions, the elevation of the serum levels of Eng and ET-1 could represent a useful tool as PAH biomarkers. Nevertheless, the diagnostic value of these markers needs to be determined by prospective studies.