A full diagnostic work-up for patients with pulmonary hypertension (PH) is vital. Classification and diagnosis of the underlying cause is important to ensure optimal management, but may be complicated by overlapping signs and symptoms. This case study describes how a full work-up identified chronic thromboembolic PH (CTEPH) as the cause of dyspnoea in a 68-yr-old male with a history of pulmonary embolism and an original diagnosis of chronic obstructive pulmonary disease. Key indicators included decreased tricuspid annular plane systolic excursion, increased Tei index and elevated systolic pulmonary artery pressure. Multi-slice spiral chest computed tomography and pulmonary angiography showed severe chronic thromboembolic pulmonary disease, both centrally and distally. Diffusing capacity of the lung for carbon monoxide was reduced and blood gas analysis revealed a wide alveolar–arterial oxygen pressure difference, which is typical of CTEPH. The patient was eligible for pulmonary endarterectomy according to established criteria. Residual PH after surgery was successfully managed with bosentan.