A man in his mid-30s was admitted with a thunderclap headache. He was conscious and hypertensive. A decade earlier, severe hypertension had been diagnosed and extensively investigated without revealing an underlying cause. Brain imaging showed subarachnoid haemorrhage caused by a ruptured pericallosal aneurysm. Endovascular occlusion was attempted, but as the sheath could not pass the aortic arch, it was converted to surgical aneurismal clipping. Intraoperative blood pressure measurement revealed a peak-to-peak gradient of 100 mm Hg across the aortic arch and an ankle/brachial index of 0.46 (normal range 0.9-1.2). Aortic coarctation was suspected, and angiographic imaging and echocardiography confirmed the diagnosis. Subacute direct stenting was performed, which normalised the peak-to-peak gradient and ankle/brachial index. To minimise the risk of severe complications, early diagnosis of aortic coarctation is important and can be facilitated by ankle/brachial index and echocardiography in the suprasternal view.