We describe the case of a 79-year-old male presented with sudden onset of abdominal pain and mild breathlessness complicated acute progressive anemia with haemoglobin declined from 120g/L to 70g/L within 5 days.An urgent computed tomography angiography (CTA) showed acute thoracic aortic dissection, DeBakey type IIIb, a dissecting aneurysm in the proximal descending thoracic aorta starting immediately after the origin of the left subclavian artery and extending distally below the renal arteries with evidence of rupture into the right pleural cavity for massive pleural effusion.Plasma D-dimer, BNP and CRP level were raised.Our case showed that D-dimer can be used as a'rule-out'test in patients with suspected aortic dissection.A raised BNP may exert a protective role through anti-inflammatory endothelial actions in the systemic circulation.