Diethylammonium p-aminobenzoate is a powerful heart stimulant, with considerable effect on the uterus. Diethylammonium p-aminobenzoate protected the heart from the poisoning caused by procaine, maxicaine or xylocaine, and also against high doses of procaine amide. The substance passes the blood-spinal fluid barrier but high doses are necessary to find it in the spinal fluid, where it appears later than in the other body fluids. Diethylammonium p-aminobenzoate reduces the spontaneous activity of mice.