A case is reported of profound accidental hypothermia with spontaneous cardiac activity in a patient presenting several risk factors. The rewarming from 23.5 degrees C to 36.5 degrees C by partial cardio-pulmonary bypass was carried out without complications and in particular without cardiac arrythmia. As far as we are aware this is the twelfth case of profound accidental hypothermia reported in the literature in which rewarming was carried out by this method and the fourth case not involving cardiac arrest. Rapid rewarming by partial cardio-pulmonary bypass could be useful in patients with profound accidental hypothermia without cardiac arrest, the most serious complication being, precisely, cardiac arrest during rewarming.