Recently, favorable outcomes have been reported after the endovascular treatment of either ruptured or unruptured paraclinoid aneurysms. The complications specifically related to the endovascular treatment of paraclinoid aneurysms have also been reported in other studies. Visual symptoms related to the mass effects associated with giant paraclinoid aneurysm normally improve after coil embolization. However, these symptoms have also been reported to be exacerbated in some cases. The authors here report an unusual case of progressive visual loss occurring after endovascular coiling treatment in a case of a large paraclinoid aneurysm.