A 43-year-old woman presented with chest pain of unclear cause. The patient's mother and brother had suffered aortic dissection. Echocardiography had shown mild dilatation of the ascending aorta at 4.0 cm. Echocardiogram and magnetic resonance imaging were negative for dissection. The patient was taken to the operating room on the basis of her painful symptoms and her family history. Unexpectedly, a localized dissection was found in the ascending aorta (see Fig 2), which was too small for imaging detection. Without preemptive surgery, full-fledged dissection would have likely occurred with attendant short and long-term consequences. This case emphasizes that size criteria pertain to asymptomatic patients, and symptomatic patients with aneurysm require resection regardless of size.