We determined the kinetics of cooling in multiple organ procurement for the kidney in a pig model. A biometric analysis by regression enables us to define the factors which influence the rate of temperature decrease: weight of the donor, average rate of perfusion and difference of temperature between the rectal temperature and the temperature of the perfusion solution at initiation of cooling. The description of the temperature as a function of time follows an exponential model of the type T(t) = T0. e(dt) where d is the rate of decrease. The rate of decrease varies according to the above factors. The cellular viability ratio (CVR), was correlated to the rate of cooling. The mean CVR was 91% (SD 4.95) when the rate of cooling was more than 1 degrees C/min. This was compared to 75% (SD 11.17) when the rate was less than 1 degrees C/min (p = 0.023). Our experience leads us to believe that the average cooling rate is frequently too low (<1 degrees C/min). This model can be used to predict and control the kinetics of cooling and may help to define the best way of cooling for future xenotransplantation.