A glc method utilizing a flame ionization detector was developed for determining ethanol (I) in rabbit arterial serum. Addition of triton X-100 solution containing the internal standard, acetonitrile (II) to rabbit serum was followed by direct injection glc analysis using Porapak Q as the stationary phase. Ethanol was clearly separated from its major metabolite acetaldehyde (III) although the assay was not suitable for determination of III. Accuracy and precision of the method was demonstrated over the concentration range anticipated in acute intravenous dosing of I to rabbits. The method was evaluated in a rabbit which received three different intravenous infusion doses of I at two week intervals and found to be applicable to arterial serum analysis.