The degree of false lumen thrombosis after surgical repair of acute DeBakey type I aortic dissection can predict long-term outcomes. However, there are currently no evidence-based recommendations for anticoagulation. We analyzed the effect of early anticoagulation on the residual false lumen and long-term outcomes.This was a retrospective observational study of 136 patients with acute DeBakey type I aortic dissection who underwent surgical repair between 1997 and 2007. We assessed the effect of early anticoagulation on the degree of thrombosis of the false lumen, segmental growth rates, repeat distal procedures, and long-term survival.Among the 136 patients who underwent operations, imaging data in 103 were sufficient for analyzing the degree of thrombosis of the false lumen. Of those, 56 (54%) received anticoagulation therapy immediately postoperatively. The early-anticoagulation group had a higher proportion of completely patent false lumens and lower partial thrombosis than the no-anticoagulation group. Mean segmental aortic growth rate was significantly lower in the early-anticoagulation group than in the no-anticoagulation group (2.9 ± 1.3 and 4.5 ± 2.8 mm/year, p = 0.0184). Overall survival and aorta-related repeat procedure-free survival were significantly better with early anticoagulation than with no anticoagulation (p < 0.05).Early anticoagulation after surgical repair of acute DeBakey type I aortic dissection might have a favorable effect on the onset or extension of thrombosis, aortic growth rate, the need for repeat distal procedures, overall survival, and thrombosis-related complications during long-term follow-up.