An arterial bypass may be required for the management of neoplastic or cerebrovascular disease. When an arterial graft is not suitable, autologous vein grafts are the most commonly used conduits; however, as many as 20% of the vein grafts used in vascular surgery may occlude as a result of subintimal hyperplasia. Although the mechanism initiating subintimal hyperplasia remains unclear, it is known that subintimal hyperplasia is dependent upon smooth muscle cell proliferation and migration from the media to the intimal layer. The present study focused on the prevention of smooth muscle cell proliferation using a calcium antagonist. Forty rats received an autologous vein bypass graft from the jugular vein to reconstruct the abdominal aorta. They were randomly divided into two groups of 20 rats each. Animals in the treated group received a calcium antagonist (nimodipine), and those in the control group received a placebo. Nine months after grafting, the group receiving the calcium antagonist presented no or only slight sub intimal hyperplasia as compared with the placebo-treated group (P less than 0.001). These data suggest that a calcium antagonist could be used for the prevention of venous graft disease.