Objective To investigate the effects of simvastatin on the expression of NOS and ICAM-1 in ischemic random skin flaps in rats. Methods 60 SD rats of both males aged 6 weeks weighing 220±20g were randomly divided into two groups with 30 rats in each group，and a random dorsal skin flap was established in each anima1. In the experimental group each rat was given a intraperitoneal injection with simvastatin (5mg/kg) and the control group animals each received the same volume of saline also by intraperitoneal injection, once a day for 7 days. The viable situation and survival rate of all flaps in the two groups were observed, meanwhile pathological changes were observed with light microscope. The full thickness flaps of tissue in the near，middle and distal segments of the flap with 0.5cm×0.5cm were immediately removed for the determination the expression of NOS and ICAM-1. Results After 7 days after operation, the changes of middle and distal segments of the flap in biopsy tip, the tissue inflammatory cell infiltration and the situation of necrosis in the experimental group were lighter than that in the control group. The survival rates of flaps and the activity of NOS were greatly higher in the experimental group than that in the control group (P＜0.05), and the activity of ICAM-1 in the experimental flap was significantly lower than the control group (P＜0.05). Conclusion Simvastatin can increase the survival rate of random skin flaps in rats, which may be related to simvastatin increased NOS, inhibition the expression of ICAM-1, thereby reducing inflammatory responses.