The history, clinical course, pathophysiology, pathology, diagnosis, and therapy of pulmonary vascular obstructive disease are presented. An explanation is provided for the terms Eisenmenger syndrome, Eisenmenger complex, and pulmonary vascular disease. The complications frequently seen in the natural history of the condition are presented, as are the therapeutic options. Despite intensive investigation of new therapeutic products, the most promising treatment for established pulmonary vascular obstructive disease remains heart-lung operation or single-lung transplant with repair of cardiac defects. Even with this option, the long-term outlook for this progressive condition remains dismal.