Thirty patients undergoing surgery were given tubocurarine chloride on a body-weight basis and were monitored electromyographically. Reversal of the neuromuscular blockage was then accomplished with incremental doses of neostigmine methylsulfate. The authors also reviewed a previous study in which the tubocurarine-induced neuromuscular blockage was reversed with neostigmine administered from 3 to 90 minutes after the tubocurarine. No precise relationship between a dose of tubocurarine based on body weight and the final degree of paralysis was observed. The optimum dose of neostigmine required to establish the complete reversal of severe neuromuscular blockade due to tubocurarine would appear to be in the region of 4 to 5 mg. This reversal can be achieved satisfactorily even when the time interval between the relaxant and antidote is only a few minutes.