We describe the case of 2 patients presenting with chest pain and electrocardiographic signs of myocardial ischemia, in whom a transthoracic echocardiogram, performed urgently at the bedside, allowed a diagnosis of dissection of the ascending aorta. Prompt recognition of this condition avoided inappropriate aggressive medical treatments and permitted emergency surgical intervention. Aortic dissection can mimic other conditions including an acute coronary syndrome. When the diagnosis is unclear it may be useful to perform a transthoracic echocardiogram before starting any aggressive medical treatment because in such cases thrombolytic or anticoagulant therapy and antithrombotic treatment with platelet glycoprotein IIb/IIIa receptor antagonists can results in serious side effects. On the other hand, transthoracic echocardiography can confirm the suspicion of an acute coronary syndrome or suggest other diagnoses such as aortic dissection.