Purpose: Diffuse mega-aorta is challenging. Prior studies have raised concerns regarding the safety of the open two-stage elephant trunk (ET) approach for extensive thoracic aortic aneurysm (TAA), specifically in regard to inter-stage mortality. This study evaluates the safety of the two-stage ET approach for management of extensive TAA. Methods: Between 2003–2018, 152 patients underwent a Stage I ET procedure by a single surgeon (mean age 64.5±14.8). Second stage ET procedure was planned in 60 patients (39.4%) and to-date has been performed in 54 patients (90%). (In the remaining patients, the elephant trunk was prophylactic for the long-term, with no plan for near-term utilization). Results: In-hospital mortality after the Stage I procedure was 3.3% (5/152). In patients planned for Stage II, the median inter-stage interval was 5 weeks (range: 0-14). Of the remaining six patients with planned, but uncompleted Stage II procedures, five patients expired from various causes in the interval period (inter-stage mortality of 8.3%). There were no cases of aortic rupture in the inter-stage interval. Stage II was completed in 58 patients (including 4 unplanned) with 30-day morality of 10.3% (6/58). Seven patients developed strokes after Stage II (12%), and three patients (5.1%) developed paraplegia. Conclusions: The overall mortality, including Stage I, inter-stage interval, and Stage II was 18.6%. This cumulative mortality for the open two-staged ET approach for treatment of extensive TAA is acceptable for aortic disease of this severity. Fear of inter-stage rupture should not preclude the aggressive Two-Stage approach to management of extensive TAA.