Résumé : A 44 year-old man came to the emergency room complaining of a sudden swelling of the sub-cutaneous soft tissue of the face and neck. He was treated with an H1 anti-histamine agent, corticoids and fresh frozen plasma. The oedema regressed favourably within a few days. The final diagnosis was angioneurotic oedema related to prior medication with lisinopril. Angiotensin converting enzyme inhibitors are increasingly prescribed. These drugs have few undesirable side effects but can lead to angioneurotic oedema in 0.1 to 0.3% of the cases. This complication is sometimes quite severe and can provoke acute obstruction of the upper airways requiring intubation. It is thus important in the emergency room to recognize this potentially mortal side effect.