A method is described which results in smooth curarization and prompt recovery using minimal amounts of tubocurarine. Following an initial dose, usually 15 mg, paralysis is maintained by a continuous infusion delivering an amount per hour about equal to the initial dose. From a mathematical interpretation of this statement an equation for the exponential disappearance of tubocurarine from the extracellular water can be obtained. Controlled ventilation is used with a light level of halothane anaesthesia. No supplementary injections of anaesthetic or analgesic are necessary. Reversal with neostigmine is prompt and complete. The accumulation curve of tubocurarine has been described and its applications stated. The time required for it to reach equilibrium between the plasma and interstitial fluid has been calculated At any time following single or multiple doses of tubocurarine, the quantity remaining in the extracellular water may be determined from the equations; this also applies to tubocurarine delivered by infusion.