The authors report 3 cases of major graft dysfunction after cardiac transplantation which recovered completely with biventricular mechanical assistance in 4 to 8 days. All three cases were primary biventricular graft failures in patients with normal preoperative pulmonary resistances. These early dysfunctions (with no signs of myocardial infarction on electro- or echocardiography and in the absence of abnormal increased peri-operative enzyme levels) associated with total functional recovery conforming to the definition of the phenomenon of myocardial stunning. These results argue in favour of aggressive management of primary graft dysfunction.