Succinylcholine-induced muscle fasciculations may be prevented by pretreatment with small doses of nondepolarizing muscle relaxants. Such pretreatment, however, may increase the difficulty of tracheal intubation by antagonizing succinylcholine (SCh) depolarization. To determine which drugs and doses best prevent fasciculation without compromising muscular relaxation, 158 healthy patients were studied before operation. Gallamine, 10–20 mg, given 3 minutes before SCh, 1.5 mg/kg, abolished fasciculations and allowed intubation under conditions equivalent to those produced by SCh, 1 mg/kg, without pretreatment-d-Tubocurarine, 3 mg, before SCh, 1.5 mg/kg, delayed paralysis. Whend-tubocurarine, 3 mg, or gallamine, 20 mg, preceded SCh, 1 mg/kg, paralysis was delayed and conditions for tracheal intubation were poor. Pancuronium pretreatment either delayed paralysis or did not consistently prevent fasciculations. Recovery of twitch response and spontaneous respiration were not significantly delayed by pretreatment with gallamine,d-tubocurarine, or pancuronium. However, hexafluorenium, 0.4 mg/kg, before SCh, 0.3 mg/kg, delayed onset of and recovery from paralysis and the return of spontaneous respiration. For clinical use, gallamine, 10–20 mg, 3 minutes before SCh, 1.5 mg/kg, is recommended.