Abstract： Objective To explore the mechanism of intestinal lesion induced by seawater immersion following open chest injury in dogs. Methods Twenty adult mongrel dogs were randomly divided into the control group (n = 10) and the seawater immersion group (n = 10). The control group was put under observation soon after abdominal injury. The seawater immersion group was immersed in manually prepared seawater immediately after abdominal injury. Arterial blood pressure and intestinal mucosa pH were monitored before injury (0 hour) and at hour4, 8, 12, and 24 after injury. Intestinal tissue samples were collected after 24 hours for the detection of MDA, NO/NOS and SOD. Results Arterial blood pressure for the animals of group B dropped significantly with statistical difference (P < 0.05), when it was compared with that of the control group. Intestinal mucosa pH of group B decreased at hour 4 with a marked difference, when it was compared with that of the control group (P < 0. 05). However, an increase was noted at hour 12 after immersion, with no significant difference, when a comparison was made between the 2 groups (P > 0. 05). Detection showed that levels of MDA, NO and NOS for the seawater immersion group increased obviously, when it was compared with that of the control (P < 0.05). Monitoring of intestinal SOD indicated that there was a clear reduction in the level of SOD for the seawater immersion group (P < 0. 05). Conclusions Trauma -induced ischemia and ischemia-reperfusion might be involved in lesion to the intestine of experimental dogs following seawater immersion.