This in vivo study confirmed impaired hemostasis during hypothermia in a swine model. Group I (normothermic, n = 8) and group II (hypothermic, n = 8) animals were anesthetized and instrumented for continuous peritoneal irrigation and monitoring of heart rate and blood pressure. The effects of hypothermia, hypotension, and inotrope on bleeding time and bleeding from two types of arterial injuries were evaluated. Our findings were that (1) bleeding time was significantly prolonged in hypothermic animals; (2) the differences in blood loss from partially torn artery (PTA) and completely cut artery (CCA) at both normothermic and hypothermic temperatures did not reach statistical significance; and (3) blood loss from PTA was greater than CCA when norepinephrine (Levophed) was infused to elevate blood pressure in hypotensive animals at normal core temperature.