The aim of this study is to investigate the clinical characteristics and postoperative outcome of patients with a bicuspid aortic valve (BAV) suffering acute dissection in comparison with their tricuspid peers. Between 1995 and 2011, 460 consecutive patients underwent emergency repair for acute type A aortic dissection. In 379 patients without connective tissue disease, the aortic valve morphology could clearly be specified (91.6% tricuspid and 8.4% bicuspid). At the time of dissection, patients with a bicuspid valve were younger (46.7 +/- 13 vs 61.6 +/- 12 years, P < 0.001) with the entry tear more often located in the root compared with those with a tricuspid valve (bicuspid: 31.3% vs tricuspid: 6.3%, P < 0.001). Consequently, surgical repair warranted root replacement in 93.8% of bicuspid vs 28.8% of tricuspid valve patients (P < 0.001). The leading pathology was medial necrosis/degeneration in bicuspid and atherosclerosis in tricuspid patients (P = 0.166). Hospital mortality was 20.3% and not significantly different between the two valve morphologies, even despite the younger age of bicuspid patients: 28.1% among bicuspids vs 19.6% among tricuspids (P = 0.255). Survival after discharge was 63.3% at 10 years for all patients. BAV patients had a significantly better survival with 100% at 10 years compared with 60.2% in tricuspid valve patients (P = 0.011). Mean follow-up among survivors was comparable for bicuspid and tricuspid patients (3.7 and 4.1 years, respectively). Patients with BAV have a distinctive dissection pattern with the entry tear frequently located in the aortic root and-despite their younger age-are subject to substantial hospital mortality. For bicuspid patients suffering from dissection, composite root replacement yields an excellent outcome equal to an age- and gender-matched normal population.