REPORTS in the lay press of the sobering effect of triiodothyronine in intoxicated humans suggested to us the desirability of investigating the effect of this compound on acute alcoholic intoxication under controlled conditions in the laboratory. To this end varying doses of triiodothyronine (3,3′,5-triiodo-L-thyronine as either the free acid or the sodium salt, obtained from Sigma Chemical Co.) were administered intraperitoneally to normal female dogs of 10–15 kgm., after which a dose of 3.0 gm. per kgm. of ethyl alcohol, diluted to 15 per cent with normal saline, was administered intravenously over a period of about 30 min. At the end of 1 hr. after the start of the injection, and afterwards each hour for 7 hr., samples of venous blood were drawn for alcohol analyses1 and the degree of intoxication assessed according to an arbitrary scale of 10 stages used for many years in this laboratory2. Controls were run on each animal, varying only in the absence of the injection of triiodothyronine.