We compared the damaging effect on myelinated nerve of alcohol and that of phenol. Guinea pigs of approximately 300 g in weight were used. Right sciatic nerve was exposed after intraperitoneal administration of pentobarbital. Saline was used in the first group as control. The second group received perineural administration of 100% alcohol. The third group received 100% alcohol inside the epineurium. The fourth group received perineural administration of 5% phenol in aqua. The fifth group received 5% phenol in aqua inside the epineurium. The first group showed no change. Toe necrosis was found in 2 cases in the second group, 3 cases in the third, null in the fourth and 6 cases in the fifth group. We concluded that damage was larger with phenol than with alcohol when administered intraneurally, but the difference was not significant. Alcohol administered inside or outside of the epineurium made no significant changes, but phenol administered only inside the epineurium made a significant damage.