Burn injury has been shown to impair gut transit, but the exact mechanism remains unknown. The present study investigated whether nitric oxide synthase (NOS) and cyclooxygenase(COX) mediated burn-induced colonic transit changes. After underwent 30% total body surface area burn injury, rats were injected with S-methylisothiourea (SMT, selective inducible NOS inhibitor), 7-Nitronidazole (7-NI, selective neuronal NOS inhibitor) and Nimesulide (NIM, selective COX-2 inhibitor), respectively. The protein and mRNA of NOS and COX-2 were measured by Western blot analysis and Real-Time RT-RCR, and localization of NOS and COX-2 protein were determined by immunohistochemistry. Our results showed that colonic transit assessed by the geometric center was delayed from 3.47± 0.28 in controls to 2.21±0.18 after burn (P<0.009). SMT and NIM significantly improved colonic transit in burn rats but had no effect in sham rats. 7-NI failed to modify delayed transit in burn rats but significantly delayed colonic transit in sham rats. Both protein and mRNA of inducible NOS and COX-2 increased significantly, but not neuronal NOS in burn rats. Inducible NOS protein expression was noted not only in epithelial cells but also in neurons of the myenteric ganglia in burned rats. These findings suggest that NO produced by neuronal NOS plays an important role in mediating colonic transit under the physiological condition. NO produced by inducible NOS and prostaglandins synthesized by COX-2 are both involved in the pathogenesis of delayed colonic transit following burn injury. Inducible NOS expression in neurons of the myenteric ganglia may contribute to dysmotility with burn injury.