The purpose of this study was to evaluate the relationship between injury to endothelial cells and the plasma endothelin level after gunshot wounds.Forty dogs were divided into four groups. The dogs in group 1 served as a control. The dogs in groups 2, 3, and 4, respectively, were shot in both hind legs, in the hypogastric part of the abdomen, or in the right chest by military bullets (5.56 mm or 7.62 mm). After wounding, blood samples were taken at different intervals and the number of circulating endothelial cells (CEC), an indicator of injury to vascular endothelial cells (VEC), and the level of plasma endothelin were measured. Results showed that the CEC number increased in all groups immediately after wounding and showed a peak value at 10 minutes and at 6 hours. The change in plasma endothelin level paralleled that of the change of CEC number, and a linear relationship was found between them. These results suggest that, in gunshot wounds, extensive injury to VEC may be the result of the temporary cavity and shock waves produced by high velocity missiles striking the body and causing secretions of endothelin. The mechanism of injury to VEC after a gunshot wound is discussed in this paper.