Aim To study the effects of basic fibroblast growth factor (bFGF) on the repairment of the injured intima by balloon denudation in rat aorta. Methods The male Wistar rats were divided into six groups as follows, two early treatment groups (a 7day-group and a 21 day-group ), one late treatment group, and three control groups including a simulated operation group. The intima of the aortae was denuded by using a balloon catheter. bFGF was injected into the tail veins of the animals on the 1st, 2nd and 3rd day (early treatment) and on 15th, 16th and 17th day after balloon denudation (late treatment ), respectively. The denuded aorta rings were perfused in the Krebs-Henseleit's balance salt bath. The plasma NO levels were determined by the method described by Green and his colleagues, and the plasma endothelin levels and the cGMP content in the aortic tissue were measured by radioimmunoassay.ResultS Intravenous injection of bFGF, not only in the early treatment but also in the late treatment,could significantly promote the relaxation reaction induced by acetylcholine. The maximal relaxation mag nitude of the denuded aorta rings in the 7-day- treatment group and 21-day-treatment group were 2. 2 and 1. 7 times that of both control groups, respectively, and the maximal relaxation magnitude in the late treatment group was 2. 6 times as high as in control group.After denudation, the plasma NO2 levels of the 7-day and 21-day control group were lower by 12% and 27%, and the cGMP contents of both control groups were lower by 57% and 48%, whereas the plasma endothelin levels of both control groups were higher by 70% and 40%, respectively, than that of the simulated operation group. Meanwhile, the plasma NO2 levels of both early treatment groups were higher by 50% and 115%, and the cGMP content of both early treatment groups were higher by 106% and 100%, respectively, than that of the control groups, whereas the plasma endothelin levels were significantly lower.The results of the late treatment group were simular to that of the early treatment groups.Conclusion Using bFGF might promote the repairment of denuded endothelium, inhibit the overproliferation of denuded intima, and therefore might play a role in preventing restenosis of balloon denuded aorta.