When chronic aortic dissection (CAD) is associated with aortic dilatation, the risk of aortic rupture increases. We report a case of CAD complicated by acute aortitis that was depicted in contrast-enhanced magnetic resonance imaging (MRI). Contrast-enhanced MRI allows early detection of subtle changes in the aortic wall as well as disease activity. Inflammation of aortic wall in the aortic dissection can be at higher risk of the dissected aortic expansion and rupture. When we recognize inflammation of unknown origin with CAD, contrast-enhanced MRI should be performed to rule out CAD complicated by acute aortitis may lead to catastrophic complications.