A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was: in patients with acute aortic intramural haematoma (IMH) is open surgical repair superior to conservative management. IMH is defined as a clinical condition related to but pathologically distinct from aortic dissection. In this potentially lethal entity, there is haemorrhage into the aortic media in the absence of an intimal tear. Altogether more than 204 papers were found using the reported search terms, from which six systematic reviews represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. IMH represents 17% of all dissections, whereas in postmortem studies this condition is found in 4-13%. The 30-day mortality of IMH is 24% (36% with type A and 12% with type B IMH; P<0.05). With surgical repair, 30-day mortality of type A IMH was 14% for patients treated surgically and 36% for patients treated medically with a P-value of 0.02. Survival at 1, 2, 3, 5 and 10 years was respectively: 81+/-21%, 87+/-8%, 83+/-6%, 65+/-22% and 44+/-14%. In contrast, with 8% mortality associated with medical treatment, prognosis of type B IMH is more favourable without surgical intervention, the latter associated with a 30-day mortality of 33% (P<0.05). Symptomatic patients and those with rapid progression or overt dissection during follow-up need emergent surgery. Ascending aortic diameter of >50 mm or subadventitial haematoma thickness of >12 mm should be considered as the candidates for early surgery. Although IMH seems to have an improved prognosis over aortic dissection, survivors of IMH are at significant risk for progressive aortic abnormalities, including aortic rupture, aneurysm, and ulceration. We conclude that surgical treatment of aortic IMH involving the ascending aorta with open distal replacement of ascending aorta results in lower mortality and longer survival compared to conservative management. IMH affecting the descending aorta can be managed with medical or endovascular interventional approach. In this latter group, serial imaging of the aorta is recommended, as aneurysm formation is not uncommon.