Patients with Eisenmenger syndrome are characterized by severe irreversible pulmonary hypertension and reversed central shunt. In the past, congestive heart failure was generally considered common and prognosis poor. However, newer information suggests that congestive heart failure is uncommon and that the natural survival of patients with Eisenmenger syndrome is better than survival achieved with transplantation. In this review, I discuss who gets Eisenmenger syndrome, when they get it, why they get it, and what the consequences are for adults with the disorder.