Ever since the demonstration of a neuromuscular action of curare by Bernard in 1856. most investigators have been preoccupied with the elucidation of the peripheral action of this drug. The central excitant action of d-tubocurarine has been generally overlooked, since the concomitant peripheral skeletal muscle paralysis produced by this agent would tend to mask any central action. However, Cohnberg (1946) reported that d-tubocurarine injected subcutaneously in rats, mice, guinea-pigs, rabbits and cats produced hyperexcitability and clonic convulsions, despite peripheral partial curarization. Baisset, Laporte & Grezes-Rueff (1949) and Nxess (1950) denied an effect of intravenously administered d-tubocurarine on the monosynaptic and polysynaptic evoked potentials recorded from ventral root. However, when the drug was localized in the central nervous system, a facilitatory action of monosynaptic extensor reflex was observed by Salama & Wright (1950). Central effects of intravenous d-tubocurarine were observed by Bernhard & Taverner (1951)