Rationale: The management of chronic thromboembolic pulmonary hypertension (CTEPH) has changed over recent years with the growth of pulmonary endarterectomy surgery and the availability of disease-modifying therapies. Objectives: To investigate the prognosis of CTEPH in a national setting during this recent period. Methods: All incident cases diagnosed in one of the 5 pulmonary hypertension centres in the UK between January 2001 and June 2006 were identified prospectively. Information regarding baseline characteristics, treatment and follow-up was subsequently collected from hospital records. Measurements and Main Results: 469 patients were diagnosed of which 148 (32%) had distal, non-surgical disease. One and three year survival from diagnosis was 82% and 70% for patients with non-surgical disease and 88% and 76% for those treated surgically (p=0.023). Initial functional improvement in patients with non-surgical disease was noted but did not persist at 2 years. Significant functional and haemodynamic improvements were seen in surgically-treated patients with an increase in six minute walk distance of 105 m (p<0.001) at 3 months. Five year survival from surgery in the 35% of patients who survived to three months but had persistent pulmonary hypertension was 94%. Conclusions: The prognosis in non-surgical disease has improved. We have confirmed the previously described good outcome in surgically-treated disease. However, we have also demonstrated that the long term prognosis for patients who have persistent pulmonary hypertension at 3 months following surgery is good. The observed improvements in outcome during the modern treatment era reinforce the importance of identifying patients with this increasingly treatable condition.