An aortic injury with concomitant pericardial tamponade caused by sternal bone marrow aspiration is rare. We report a case of fatal sternal bone marrow aspiration performed to a 73 year old man for the purpose of confirming the diagnosis of multiple myeloma. This puncture was followed by an injury in the aorta causing a pericardial tamponade and the death of the patient immediately after the aspiration. This paper stresses the precautions to be taken, by the operator, in certain particular situations that make the sternal bone marrow aspiration difficult and risky, and discusses the different types of operator´s liability that can be involved and their foundations.