Background.　Free　skin　graft　has　to　be　used　when　the　large　area　skin　are　burned.　The　objective　of　this　study　is　to　quantify　the　influence　of　free　graft　and　expansion　on　the　skin　biomechanical　remodeling.　Method.　Four　white　pigs　(weighing　from　17　kg　to　23　kg)　were　used.　Two　180　ml　rectangle　expanders　were　aseptically　placed　beneath　the　skin　on　the　back　of　each　pig.　Four　normal　skin　flaps　and　four　expanded　skin　flaps　were　incised　from　the　foreside　back　of　each　pig.　Two　normal　skin　flaps　and　two　expanded　skin　flaps　were　then　grafted　to　rearward　back　of　the　pig.　Stress-strain　relationship,　stress　relaxation　and　creep　characters　in　normal　skin:　N(n　=　8),　expanded　skin　without　graft:　E(n　=　8),　normal　skin　with　free　graft　after　three　months:　NG(n　=　8)　and　expanded　skin　with　free　graft　after　three　months:　EG(n　=　8)　were　measured　by　using　Instron　material　testing　machine.　Findings.　The　strains　at　3.5　MPa　stress　(mean　(SD))　are　0.4436(0.1760),　0.4851(0.1401),　0.7750(0.1984)　and　0.5854(0.0655)　respectively　in　N,　E,　NG　and　EG　groups.　The　maximum　relaxations　(mean　(SD))　are　0.6324(0.0169),　0.6279(0.0401),　0.5630(0.0170)　and　0.6057(0.0883)　in　N,　E,　NG　and　EG　groups,　respectively.　The　maximum　creeps　(mean　(SD))　are　1.0876(0.0086),　1.1037(0.0116),　1.1948(0.0394)　and　1.1328(0.0223)　in　N,　E,　NG　and　EG　groups.　Interpretation.　The　biomechanical　characteristics　of　free　graft　with　expanded　skin　after　three　months　have　no　significant　difference　with　the　normal　skin,　expansion　skin　and　free　graft　with　normal　skin　after　three　months　(P　＞　0.05).　The　free　graft　and　expansion　have　no　significant　influence　on　the　skin　biomechanical　remodeling.　(c)　2006　Elsevier　Ltd.　All　rights　reserved.