Aortic dissection is one of the true surgical emergencies that still exists in the field of cardiac surgery. Any busy practice can say that there are patients frequently turning up in the emergency department with acute and chronic aortic dissection. Smaller practices may not get as much exposure to this type of pathology. In speaking to the emergency department and to transferring hospitals, I have come to understand that there is some confusion among the medical community in general, and perhaps even in the cardiac surgery community, regarding the appropriate classification of aortic dissection. I thought a brief primer in classification might be a useful review.