Background Thoracic aortic dissections (TADs) and thoracic aortic aneurysms (TAAs) are resource intensive. We sought to determine economic burden and healthcare resource use to guide health policy. Methods and Results Using universal healthcare coverage data for Ontario, Canada, from 2003 to 2016, a cost-of-illness analysis was performed. From a single-payer's perspective, direct costs (hospitalization, reinterventions, readmissions, rehabilitation, extended care, home care, prescription drugs, and imaging) were assessed in 2017 Canadian dollars. Controls without TADs or TAAs were matched 10:1 on age, sex, and socioeconomic status to cases with TADs or TAAs to compare posthospital service use to the general population. Linear and spline regression were used for cost trends. Total hospital costs increased from $9 M to $20.7 M for TADs (P<0.0001) and $13 M to $18 M for TAAs (P<0.001). Costs cumulated to $587 M for 17 113 cases. Median hospital costs for TADs were $11 525 ($6102 medical, $26 896 endograft, and $30 372 surgery) with an increase over time (P=0.04). For TAAs, median costs were $16 683 ($7247 medical, $11 679 endograft, and $22 949 surgery) with a decrease over time (P=0.03). Home care was the most used posthospital service (TADs 44%, TAAs 38%), but rehabilitation had the highest median cost (TADs $11.9 M, TAAs $11 M). Men had increased median costs for indexed hospitalizations relative to women, yet women used more posthospital services with higher service costs. Conclusions Total yearly costs have increased for TADs and TAAs. Median hospital costs have increased for TADs yet decreased for TAAs. Women use posthospital healthcare services more often than men.