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Background The endothelin system (ES) plays an important role in blood pressure (BP) regulation and also in the pathophysiology of idiopathic dilated cardiomyopathy (DCM). Recently, we demonstrated that a genetic polymorphism in the endothelin A (ET A ) receptor gene was associated with survival in DCM patients. The aim of this study was to determine whether polymorphisms in the ET A receptor gene might be associated with the severity of DCM. Methods One hundred twenty-four consecutively recruited unrelated patients with DCM, who underwent a detailed phenotyping protocol, were genotyped for the ET A receptor G-231A polymorphism using a hybridization technique with allele-specific oligonucleotides. Results The exon 1 G-231A polymorphism of the ET A receptor gene, upstream of the translation start site, was significantly associated with directly measured intra-aortic pressure in that −231A allele carriers had significantly lower systolic ( P = .0043), as well as mean ( P = .0016) and diastolic ( P = .0041) aortic pressure compared to noncarriers. The association of ET A G-231A with aortic pressure was independent from other factors such as prior medication, left ventricular end-diastolic diameter, age, gender, and New York Heart Association (NYHA) functional classification. However, no such association was seen for cuff BP and survival rates were not significantly different between −231A allele carriers and −231G homozygotes (log rank test, P = .66). No significant association with any other parameter investigated in the present study could be observed, even when men and women were analyzed separately. Conclusions Our results suggest an association of genetic variation in the ET A receptor gene with aortic pressure in patients with DCM.