Postoperative muscle pain is well known to occur in man following intravenous administration of succinylcholine. The mechanism of muscle pain is yet unknown. A number of methods for preventing muscle pains or decreasing their severity have been suggested, including nondepolarizing relaxants prior to succinylcholine (Churchill-Davidson, 1954: Cullen, 1971: Wig and Bali, 1979) or lidocaine(Usubiaga et al., 1967: Haldia et al., 1973: Fry, 1975), use of vitamin C (Gupte & Savant, 1971), procaine chloride(Morris & Dunn, 1957), thiopental sodium (Craign, 1964) or diazepam (Verma et al., 1978) and the use of a "self-taming" method of succinylcholine by prior injection of a small dose(Baraka, 1977). To investigate methods of preventing muscle pains or decreasing their severity after intravenous injection of succinylcholine, we studied four groups, a control group and three experimental groups (a lidocaine group, a d- Tubocurarine group and a succinylcholine self-taming group). The following results were obtained: 1) In the lidocaine group, the incidence of muscle pain was lower than in the control group, but there was no significant difference between the two groups. However the incidence of muscle pain in the d-Tubocurarine group or the succinylcholine self-taming group were lower than in the control group and there were statistically significant differences(p<0.0005). 2) In most of the patients of each group, the degree of postoperative muscle pain was mild and a difference of degree of muscle pain was not found in each group (p>0.05).3) The muscle pain usually appeared in the first day after operation and disappeared usually within three days. 4) The degree of muscle fasciculation showed a significant decrease with lidocaine, d-Tubocurarine or the succinylcholine self-taming group over the control group(p<0.0005), but there was no significant relationship between the degree of muscle fasciculation and the incidence of postoperative muscle pain(p>0.05). 5) The degree of muscle relaxation during intubation in the d-Tubocurarine group was less complete than in the other 3 groups and it was statistically significant(Zi>1.96). It is suggested from the above results that d-Tubocurarine(0.05~0.06mg/kg) prior to succinylcholine or the method of self-taming of succinylcholine(prior use of succinylcholine 0.15mg/kg) can be used as methods to prevent muscle pain after intravenous administration of succinylcholine, but lidocaine(2mg/kg) prior to succinylcholine is not effective in preventing muscle pain following succinylcholine administration.