BACKGROUND: Stent-graft treatment for aortic disease promises to lead to a less invasive therapy than conventional surgical therapy. However, this treatment has not been established as a therapy for aortic dissection. The aim of this study was to examine the effect of stent-graft treatment of aortic dissection, as measured by follow-up data on entry site closure, clotting in the false lumen, and the outcome of the false lumen from the acute to chronic phase after operation. METHODS AND RESULTS: We used a stent-graft of our own design to close the entry site of aortic dissection in 21 cases: 9 were acute (< 14 days), 8 subacute (< 6 months), and 4 chronic (> 6 months). Nine were type A and 12 were type B. In 15 cases, the stent-graft was inserted through the transverse arch, which had been surgically opened under median sternotomy. In the other 6 cases, the stent-graft was inserted by means of a transcatheter through a femoral artery. Using computed tomographic scans, we followed and examined clot formation in the false lumen and reduction in size of the false lumen at 3 levels: at the level of maximum aortic diameter, at the distal end of the stent-graft, and 50 mm distal to the stent-graft. The entry sites were successfully closed in 19 cases (90.4%); in the remaining 2 (both treated with a transcatheter) there was perigraft leakage into the false lumen. The hospital mortality rate of these stent-graft treatments was 14.3% (3 of 21). At 2 weeks after operation, the false lumen had completely clotted, respectively, in 100%, 77%, and 38% of cases at the 3 measurement levels. Substantial shrinkage (> 50% in diameter) of the false lumen at 6 months after the operation was observed in 72%, 60%, and 38% of cases at the respective levels. Shrinkage of the false lumen was particularly enhanced in patients treated within 6 months from the onset of dissection: The false lumen shrank by > 50% in 93%, 75%, and 50% of patients. CONCLUSIONS: In cases of aortic dissection, the stent-graft is an effective tool for closing the entry site and promoting clot formation in the false lumen and for reducing the size of the false lumen within 6 months of the onset of dissection if the entry site has been closed.