The effect of hypothermia (29 C) on the pharmacokinetics of ethanol was studied in eight piglets serving as their own normothermic controls. Ten milliliters of 12% ethanol per kilogram were infused over 30 minutes, and serum ethanol concentrations were measured for seven hours. Ethanol concentration data were fitted to one-compartment open model assuming Michaelis Menten elimination kinetics. During hypothermia, ethanol concentrations were consistently higher than during normothermia. This observation could be explained by both a significantly smaller distribution volume of ethanol during hypothermia (0.71 +/- 0.03 L/kg at 29 C and 0.84 +/- 0.05 L/kg at 37 C, P less than .02) and a significantly slower maximum velocity of metabolism of ethanol (Vm) during hypothermia (1.12 +/- 0.11 mg/kg.min vs. 1.83 +/- 0.21 mg/kg.min, P less than .01). Our study indicates that during hypothermia, ethanol stays significantly longer in the circulation in piglets. Potentially, this may contribute to a more profound effect from the ethanol.