Hereditary haemorrhagic teleangiectasia (HHT) or Rendu-Osler-Weber disease is a rare and underdiagnosed disorder with an autosomal dominant pattern of inheritance. HHT is characterised by presence of vascular malformations in the skin, as well as in the nasal and oral mucosa, the gastrointestinal tract, the liver, the brain and the lungs. Pulmonary arteriovenous malformations (PAVM) provide right-to-left shunts leading to hypoxemia and emboli in systemic circulation that lead to clinical consequences, such as ischaemia and abscesses, particularly, in the brain. This article provides an overview of the underlying genetics, pathophysiology, clinical presentation, diagnosis (as well as the indication for screening tests) and treatment of HHT with special regard to the diagnosis and management of PAVM. Trans-catheterembolization of PAVM is the mainstay of treatment of HHT and aims at preventing severe complications such as brain abscesses and ischaemic lesions, correcting/diminishing hypoxaemia. Embolization of PAVM is therefore warranted even in asymptomatic patients. Two cases of HHT with vascular malformations in the lungs are reported. Both cases were diagnosed after the development of complications.