We investigated the influence of pre-harvesting general hypothermia on liver metabolic activity by means of Aminopyrine Breath Test (ABT). This study was conducted in pigs which were anesthetized, curarised and cooled on an ice bed. Each animal received labelled aminopyrine and 14CO2 in expired air was measured between 37.5 and 25.5 degrees C. The liver metabolic activity at 31.5 degrees C represents 53.3% of the normothermic value. At 25.5 degrees C, this activity is reduced by 75.1%. The mean decreasing rate is 6.2%/degrees C for a fall in temperature of 12 degrees C. A change of slope occurred at 31.5 degrees C. The first decreasing rate is 7.47 +/- 1.62%/degrees C and the second one is 4.48 +/- 2.27%/degrees C. Thus, use of general hypothermia during liver harvesting should improve the quality of organ preservation: the important reduction of metabolism should decrease the oxygen debt resulting from anaerobic cold perfusion.