Objective To observe effects of meshed relaxing short incisions (MRSI) on the content of endothelin (ET) in rat tension skin flap,and to investigate the mechanism of meshed relaxing short incisions(MRSI) on wound healing process of tension skin flap.Method We designed an experimental model to investigate the change of ET content caused by MRSI and observe the distribution of ET in rat skin flap tissue each period of wound healing.In the meantime,the immunohistochemistry and auto image analysis were employed.Results Our results showed:(1) ET positive immunologic reaction granules involved in small vascular endothelial cell in rat skin flap tissue increased with prolonging of time within 3 days;(2) the content of ET in MRSI group were significant lower than that of hypertension group (P< 0.05) .Conclusion The decrease of ET contents may be one of the causes that MRSI improves microcirculation of skin flap, and reduces edema and facilitates healing of skin flap.