In avalanche accidents the cause of cardio-respiratory arrest (asphyxia, hypothermia, trauma) is difficult to determine in the field but may be important (high number of victims, limited number of rewarming places). 32 avalanche accidents (16 survivors/16 deaths) were therefore reviewed retrospectively. In 19 patients with cardiorespiratory arrest, asphyxia was frequent (17 patients, 89%) hypothermia was rare (two patients, 11%). The cooling rate between the accident and the arrival at the hospital was 3.0 degrees C/h. (range 0.75-5.8). The core temperature at arrival in the hospital was dependent on the time spent buried under the snow (survivors) and total time (nonsurvivors). The maximal cooling rate under the snow was estimated at 8 degrees C/h. Cardiorespiratory arrest in hypothermic patients without asphyxia seems only to be possible after being buried for at least 1 h. under the snow. Serum potassium was elevated in most cases of asphyxia.