We report a quite rare case of giant extracardiac unruptured aneurysm of the right coronary sinus of Valsalva with no clinical findings of Marfan syndrome or Ehlers-Danlos syndrome. A 52-year-old Chinese male was diagnosed having an aneurysm of the right sinus of Valsalva and moderate aortic regurgitation, while Bentall operation was performed successfully. The patient was discharged with no complications. Pathological examination revealed conspicuously medial mucoid degeneration of the aneurismal wall and absence of medial elastic fibers. Immediate results and early follow-up were uneventful.