Trimethylamine hydrochloride (TMA) injected intravenously accelerated flow of the thoracic-duct lymph in a dog in doses above 25 mg./kg. The effect of 50 mg./kg. of TMA was comparable to that produced by about 0.05 mg./kg. of adrenaline. The thoracic-duct lymph increased by TMA was rich in protein concentration and showed tendency for facile coagulation, as lymph accelerated by adrenaline. A small amount of TMA decreased arterial blood pressure but in a dose effective to lymph flow, the blood pressure increased markedly after a transitory fall, with an attendant rise of portal blood pressure. In such a dose, decrease in the volume of the liver and intestines was observed. Except for the initial fall of arterial blood pressure, these actions were the same as those caused by adrenaline. Atropine suppressed not only the lymphagogic action but also the rise of arterial and portal blood pressure by TMA. Similar suppressive action was also observed under the action of TEA or hexamethonium. Dibenamine strongly suppressed the rise of arterial blood pressure by adrenaline and by TMA but its suppression was incomplete against the rise of portal blood pressure and lymphagogic action. In adrenalectomized dog, the lymphagogic action and rise of arterial and portal blood pressure by TMA did not appear at all. These observations indicate that the acceleration of thoracic-duct lymph flow by TMA is mediated by the liberation of epinephrine from the adrenals in the dog.