Replantation after crushing amputation has a relatively low success rate. Although the mechanism of trauma is a major factor in failure, the time lapse before vessel anastomosis may also be a contributing factor. In this study, we observed the influence of the interval between vessel injury and surgical treatment on thrombus formation and healing after controlled crushing. Seventy-five Sprague-Dawley rats were used. A segment of femoral artery was clamped to create warm ischemia for 8 hours and crushed with a 15 kg load for one hour. After the loading device was removed the crushed segments were transected and the vessel ends exposed to the adjacent tissues and blood for 0, 2, 4 and 6 hours (groups II-V, respectively) prior to being anastomosed with standard microsurgical technique. The vessel samples were harvested at days 1, 2 and 7, respectively, and evaluated by light microscopy and scanning electron microscopy (SEM). The patency rate of the anastomoses was 97.3% at harvest and reendothelialization was completed at day 7. Three anastomoses with 4 or 6 hours exposure showed thrombosis, or clotting. The results indicated that up to 6 hours exposure time did not have a significant influence on thrombus formation or the healing process of vessels under the controlled conditions of this study.