Plasma cortisol concentrations were measured in nine dogs after high-velocity missile injury induced by spherical steel bullets. All nine dogs sustained soft-tissue wounds in the thighs without damage to large vessels, femur, or nerves. When the dogs were considered as one group the mean plasma cortisol concentration increased promptly 10 min after injury (p less than 0.05) and reached its peak at 1 hour and then decreased. The mean concentration at 6 hours after injury was still higher than that before injury (p less than 0.05). Even though the severities of the injuries varied rather much there was a significant difference (p less than 0.01) between the plasma cortisol concentrations at 1 hour of the two groups into which the dogs were divided according to the severity of their injuries. The changes of the plasma cortisol concentrations may be parallel with the extent of the injuries and there was a positive correlation with the dimensions of the entrance wounds.