ObjectiveTo evaluate the effect of low power red laser illumination on the intimal proliferative response in vein graft models.MethodsAutogenous vein graft models were established in 80 rats by transplanting jugular vein to carotid artery by end to end anastomosis, and were randomized into two groups: control group (graft nonilluminated), laser illumination group (0.9 J/cm2).The grafted veins were harvested at 3,7,14 or 28 day respectively after operation. IH (intimal hyperplasia) and SMC (smooth muscle cell) proliferations were pathologically and immunohistochemically observed and analyzed by computer digitizing system. ResultsThere were no significant differences in the intimal average thickness and the areas of lumen between two groups for 3 day. Laser group was significantly lower than the control in both the intimal average thickness and the stenosis of lumen at 7 day,14 day and 28 day (P＜0.05).Immunohistochemical analysis of PCNA indicate the decreased positive cell in laser group compared with the control group (P＜0.01).ConclusionThese preliminary results demonstrate that a certain density of low power red laser illumination in vein graft inhibits SMC proliferation and neointimal hyperplasia in rat.