My interest in the use of procaine to control pruritus has extended over a long period. Recently my colleagues and I1 reported on the use of intravenous procaine hydrochloride and are now studying the effects of orally administered procaine-ascorbic-acid combination. This present report deals with the use of a new local anesthetic solution, Efocaine. This product is a combination of procaine base and butyl p-aminobenzoate, which are insoluble in water, but are soluble in the aqueous miscible nontoxic organic solvents, propylene glycol and polyethylene glycol. This solution is at saturation limits, so that when injected into the tissue the contact with aqueous tissue fluids causes the complete precipitation of the active ingredients. The inert solvents are rapidly absorbed and excreted, leaving a microcrystalline drug repository along the lines of injection. The anesthetic depot is slowly absorbed, its effects continuing for a prolonged period. The mechanism of action