We describe a giant unruptured acquired aneurysm of the noncoronary sinus of Valsalva, which was detected incidentally in a 30-year-old rugby player with clinical suspicion of dermatomyositis. Sixty-four-slice cardiac computed tomography showed a giant aneurysm (diameters: 91 x 78 x 100 mm) of noncoronary sinus of Valsalva compressing both atrial chambers. The patient underwent cardiac surgery according to the Tirone David technique based on the information provided by cardiac computed tomography.