An attempt was made to correlate the incidence of muscle pain following the administration of succinyIcholine and its prevention by prior administration of gallamine or d-tubocurarine. The overall incidence of pain after use of succinylcholine was 29 per cent. The prior injection of d-tubocurarine (0. 05 mg/kg) or gallamine (0. 3 mg/kg) completely pervented the muscle pain. It is presumed that d-tubocurarine or gallamine protects the patients from muscle pain by preventing a portion of the injected succinylcholine from depolarizing the muscle fibers.