The ESS-1 study was designed to evaluate the long-term effects of the angiotensin converting enzyme inhibitor (ACEI) enalapril (10 mg per day) on the cardio-pulmonary system in patients with scleroderma (SSc). We estimated changes in heart diameters, systolic and diastolic left ventricle function and mean values of pulmonary artery pressure after 3 months treatment. The study group comprise 41 patients with SSc. 18 patients received placebo and 23 ones were given enalapril. After 3 months of treatment we did not observe statistically significant differences in heart diameters and left ventricle systolic function parameters between treated group and placebo. Enalapril therapy did not affect left ventricle diastolic function, nevertheless differences in MVA were almost of statistical significance. Echocardiographic signs of pulmonary hypertension were found in 4 patients.