We describe a 59-year-old patient with Holmes heart (single ventricle with normally related great arteries). To our knowledge, this is the oldest patient in the literature with this rare congenital heart disease and the oldest one with single ventricle and unrestricted pulmonary blood flow who has developed Eisenmenger's physiology. A transesophageal echocardiographic examination showed a single large ventricle that was a morphologic left ventricle with a normally appearing aorta originating from this chamber and a normally related pulmonary artery arising from a hypoplastic right infundibulum located anteriorly-superiorly and to the left of the left ventricle. The cardiac catheterization confirmed the echocardiographic findings and revealed a pulmonary artery pressure of 160/60 mmHg. There were no systolic gradients across the pulmonary and aortic outflow tracts. The estimated pulmonary vascular resistance was 2720 dynes-sec-cm-5. Oximetry showed oxygen saturation in the left ventricle of 84% and femoral artery saturation of 77.7%. Our report further demonstrates that pulmonary stenosis is not the ultimate determinant of prolonged natural survival in patients with single ventricle. Since this patient is too old for cardiopulmonary transplantation, we plan to follow him conservatively with medical therapy.