Severe crush injury is associated with high mortality because of resulting hyperkalemia in early phase and multiorgan dysfunction in later phase. In this study, we investigated the effects of sivelestat administration 1 h before reperfusion on the outcome of crush injury. Crush injury was induced by 6 h of direct compression to both hindlimbs of anesthetized rats with blocks weighing 3.5 kg each side, followed by 3 h of reperfusion. Rats were randomly assigned to three groups. In the control group, rats were infused with normal saline at 1 mL/kg per hour throughout the experiment without compression. Rats in the positive control group were compressed for 6 h, followed by fluid resuscitation initiated 1 h before release with normal saline. The infusion rate was increased from 1 to 10 mL/kg per hour and continued for 4 h. Rats in the treated group underwent the same procedures as in the positive control group, but sivelestat was added to normal saline (concentration was adjusted to infuse 10 mg/kg per hour) during fluid resuscitation (for 4 h). Treatment with sivelestat significantly improved survival rate with P = 0.032. This was accompanied by lower serum high-mobility group box 1 (HMGB1) levels after 3-h reperfusion, attenuated lung injury (assessed using hematoxylin-eosin stain), and suppression of HMGB1 expression in the lung and the liver. These results suggest that treatment with sivelestat improves the outcome of crush injury, likely by inhibiting HMGB1 in rats.