We determined the effects of ibuprofen and methimazole on the formation of second- degree burn edema. Two small burns were produced on the back of rats. Ten minutes prior to burn, Evans blue ( EB) dye was injected through a femoral vein catheter. All animals were extravasation of evans blue. Ten groups of rats were studied. Immediately after induction of burns, test drugs were administered intraperitoneally. The results showed that, ibuprofen (12 mg/ kg) effectively decrease E.B. extravasation in test group s compared to the control group ( 14.1 mg/100 mg skin vs 35.5 +_2.3 mg/100 mg skin). Methimazole (1 mg/ kg) also decrease E.B extravasation compared to the control ( 28.7+_1.2 mg/100 mg skin v.s 35.5+_2.3 mg /100 mg skin). Comparison between these drugs showed that ibuprofen appeared to the more potent than methimazole. Similar water content of control and test group indicatas that these drugs did not reduce water content in burned skin. Certainly, a discrepancy was observed between protein leakage and accumulation of fluid. These data support this postulation that inhibition of arachidonic acid metabolism in site of cyclooxygenase was much more effective than inhibition of thromboxan synthetase.