Eisenmenger syndrome (ES) is the most advanced form of pulmonary arterial hypertension (PAH) associated with congenital heart defects. ES greatly affects functional capacity, quality of life, and survival of patients. Clinical management of patients with ES has been dramatically changed and developed in a new therapeutic era of PAH, approximately a century after the first ES case described by Dr. Eisenmenger. Targeted drugs for PAH improve functional capacity and quality of life of patients with ES. In addition, these drugs may also provide a benefit for patients' survival. To achieve further development in medical treatment of patients with ES, they will need to be individualized according to functional classes, underlying cardiac defects, and underlying systemic diseases.