The elimination of ethyl, n-propyl, n-butyl and iso-amyl alcohols has been investigated over a dose range in the isolated perfused rat liver. The elimination of ethanol was saturable with a zero-order phase being succeeded below a concentration of 5 mmol by an exponential phase. The elimination of n-propyl, n-butyl and iso-amyl alcohols was similar. There was an increasing affinity of the alcohol to the rate-limiting process with increasing carbon chain length of the alcohol. The apparent Michaelis constants for the alcohols were similar to those determined in vitro with the enzyme alcohol dehydrogenase. The addition of ethanol simultaneously with either n-propyl, n-butyl or iso-amyl alcohol was associated with a reduction in the rate of elimination of both ethanol and the higher alcohol. Changes in the apparent Michaelis constant (KM) in the absence of changes in the apparent maximal velocity (Vmax) suggested competitive inhibition for the elimination process.