Increased plasma levels of adrenomedullin (ADM) have been reported in patients with congestive heart failure Immunohistochemical ADM has been identified in failing human ventricle, but the gene expression pattern of ADM messenger RNA (mRNA) in myocardial tissue of patients with heart failure has not been elucidated. In this study, gene expression of ADM mRNA (analyzed by northern blot) and tissue concentration of ADM (measured by radioimmunoassay) were assessed in the explanted hearts of 17 patients with idiopathic dilated cardiomyopathy (IDC) and in 7 organ donors with no cardiopathy (controls). Myocardial tissue samples of patients with IDC showed increased ADM mRNA gene expression (p < 0.05) and decreased immunoreactive ADM protein content (p < 0.02) compared with controls.