ABSTRACT: New anesthetics have been introduced during the last 25 years which are not without inherent disadvantages. They are expensive, and some produce nephrotoxicity and possibly hepatotoxicity. Although the use of procaine intravenously as an anesthetic has been discarded, probably because of a convulsive effect, it is believed this disadvantage can be controlled by concomitant use of other drugs. Hence procaine, preceded by thiamylal, was administered to dogs to test its anesthetic capability, reversibility, and effects on the cardiovascular and central nervous systems. Blood levels of procaine were measured and correlated with these physiologic responses. Convulsive doses were ten times those producing anesthesia. There were no detrimental effects which would preclude a reevaluation in humans. Intravenous procaine produces definite general anesthesia, and it has the additional advantages of being rapidly hydrolyzed and providing antiarrhythmic effects. It may prove useful in modern anesthesia.