This case report describes the successful treatment of severe accidental hypothermia of a 40-year-old woman. At arrival in the operating theatre her rectal temperature was 23 degrees C, her nasal temperature 21 degrees C and her periferal temperature 14 degrees C. The patient presented with a severe respiratory and metabolic acidosis which was corrected during cardiopulmonary bypass (CPB). She was rewarmed to obtain a rectal and nasal temperature of 34 degrees C. After 272 minutes, the patient was weaned successfully from CPB. The patient remained at mild hypothermia (34 degrees C) for 24 hours in the intensive care unit (ICU). The chest X-ray showed some signs of acute respiratory distress syndrome (ARDS) in spite of normal blood gas values. This improved within a few days and, after five days, she was transferred to the nursing department. On the seventh day, the patient was discharged from hospital without physical or neurological complaints.