Acute type B aortic dissection can be treated with medical management alone, open surgical repair, or thoracic endovascular aortic repair (TEVAR). The nationwide burden of readmissions after acute type B aortic dissection has not been comprehensively assessed.We analyzed adults with a hospitalization due to acute type B aortic dissection between January 1, 2010, and December 31, 2014, in the Nationwide Readmissions Database. International Classification of Diseases, Ninth Revision, Clinical Modification codes were used to identify hospitalizations with a primary diagnosis code for thoracic or thoracoabdominal aortic dissection. The primary outcome was nonelective 90-day readmission. Predictors of readmission were determined using hierarchical logistic regression.The study population consisted of 6937 patients with unplanned admissions for type B aortic dissections from 2010 through 2014. Medical management alone was the treatment for 62.6% of patients, 21.0% had open surgical repair, and 16.4% underwent TEVAR. Nonelective 90-day readmission rate was 25.1% (23.6% with medical management alone, 26.9% with open repair, and 28.7% with TEVAR; P < .001). An additional 4.7% of patients were electively readmitted. The most common cause for nonelective readmission was new or recurrent arterial aneurysm or dissection (24.8%). Of those with unplanned readmissions, 5.2% underwent an aortic procedure. The mortality rate during nonelective readmission was 5.0%, and the mean cost of the rehospitalization was $22,572 ± $41,598.More than one in four patients have a nonelective readmission 90 days after hospitalization for acute type B aortic dissection. Absolute rates of readmission varied by initial treatment received but were high irrespective of the initial treatment. The most common cause of readmission was aortic disease, particularly among those treated with medication alone. Further research is required to determine potential interventions to decrease these costly and morbid readmissions, including the role of multidisciplinary aortic teams.