To investigate the effect and the relevant potential mechanism of nonpeptide neurokininl(NK1) receptor antagonist L-703,606 in the edema formation after burn injury,L-703,606 treatment was performed in Sprague-Dawley (SD) rats at early stage after deep partial-thickness skin scalding.One hundred and fifty two adult male SD rats were used in the study and randomly divided into sham scald (SS, n=8), scald control (SC, n=48), L-703,606 treatment (LT, n=48) groups.The rats in SC and LT groups were subjected to 20% total body surface area (TBSA) deep partial-thickness skin scalding.Modified Evans blue extravasation, tracing electron microscopy by lanthanum nitrate and mean water content assay were employed to observe and detect the changes of vascular permeability,ultrastructure and edema formation in adjacent tissue to the wounds and in the jejuna of rats at early stage (72 h) after scald.