We describe a patient with large sinus of Valsalva aneurysms involving both the left and right coronary sinuses. Spontaneous dissection of the left coronary artery occurred, causing unstable angina, a complication heretofore not associated with this disease. Successful surgical reconstruction of the aortic root, aortic valve replacement, and coronary bypass grafting were performed. Pathology revealed cystic medial necrosis.