The ethanol disappearance rate was determined in fed rats given 20-40 mM ethanol and anesthetized with pentobarbital (control group) and diethyl ether. The control ethanol disappearance rate was 0.27 +/- 0.02 mM/min (+/- SD, n = 4). Rats anesthetized with diethyl ether (blood levels of 9-13 mM) revealed an ethanol disappearance rate of 0.13 +/- 0.05 mM/min (+/- SD, n = 7), i.e., 52% inhibition of the control rate. Kinetic studies on crystalline and lyophilized alcohol dehydrogenase from equine liver demonstrated that 20 mM diethyl ether inhibited the initial rate of ethanol oxidation by 55%. By using ethanol as the variable substrate the inhibition of alcohol dehydrogenase was described by a mixed noncompetitive/uncompetitive mechanism.