Autologous vein grafts are commonly used conduits for coronary bypass grafts. However, as many as 20% of the grafts may occlude in the first year to a subintimal hyperplasia. Although the initiating mechanism remains unclear, it has been demonstrated that subintimal hyperplasia is dependent upon smooth muscle cell proliferation and migration from the medial to the intimal layer. The present study focused on the prevention of smooth muscle cell proliferation using a calcium antagonist. A vein bypass graft from the jugular vein on the abdominal aorta was performed in 40 rats, divided into two groups of 20. Animals in the treated group received nimodipine (15 mg/kg of body weight), and those of the control group received a placebo. Nine months after grafting, the results showed that the group receiving nimodipine presented no or only slight subintimal hyperplasia as compared with the placebo group (p less than 0.001). The data presented in this study show that nimodipine can reduce subintimal hyperplasia in rats and strongly suggest that a calcium antagonist could be employed in the prevention of venous graft disease.