The purpose of this study was to report the pharmacokinetic changes of cyclosporine after oral administration of cyclosporine, 10 mg/kg, in rabbits coadministered or pretreated twice per day for 3 days with nimodipine, dose of 5 mg/kg. The area under the plasma concentration-time curve (AUC) of cyclosporine was significantly higher in rabbits pretreated with nimodipine than that in control rabbits (p＜0.01), showing about 149％ increased relative bioavailability. The peak plasma concentration (C$_{max}$), elimination half-life (t$_{1}$2/) and MRT of cyclosporine were increased significantly (p＜0.05) in rabbits pretreated with nimodipine compared with those in control rabbits. This findings could be due to significant reduction of elimination rate constant and total body clearance by pretreated with nimodipine. The effects of nimodipine on the pharmacokinetics of oral cyclosporine were more considerable in rabbits pretreated with nimodipine compared with those in control rabbits. The results suggest that the dosage of cyclosporine should be adjusted when the drug would be coadministered chronically with nimodipine in a clinical situation.n.