Pulmonary thromboendarterectomy surgery is the recommended treatment for patients with chronic thromboembolic pulmonary hypertension. Massive intraoperative pulmonary haemorrhage with bleeding into the airway is a rare complication, and it typically presents as cardiopulmonary bypass flow is reduced and blood begins to flow through the pulmonary circulation. Immediate management includes maintaining extracorporeal circulation to reduce blood flow through the pulmonary circulation, isolation of the affected lung, while the surgeon identifies and repairs the site of haemorrhage.