The optimization of cyclosporine-A (CsA) immunosuppression remains a challenge because of the narrow therapeutic window and highly variable pharmacokinetics. During the past decade ,various pharmacokinetic strategies have been proposed ,such as trough level (C₀) monitoring , single point concentration at 2 hour postdose(C₂) after drug administration, and various sampling algorithms using 2 to 5 sampling time points. In this study we evaluated the cyclosporine-A pharmacokinetic in stable Iranian children recipients of renal transplant. Subjects and methods A total of 29 stable renal transplant recipients (age 3-12 years) whose serum creatinine values were <2 mg.dL^-1 were the subjects of this investigation. All the cases had renal transplants more than 6 months ago. The subjects received cyclosporine-A based immunosuppression with Ne. Blood samples were collected at 5 points predose, 0.5, 1, 2 and 4 hours after drug administration at clinical steady state. Whole blood cyclosporine-A concentrations were measured using Radioimmunoassay for cyclosporine (Cyclo-Trac^R SP-Whole blood ¹²⁵I RIA kit, Stillwater, USA). Cyclosporine-A exposure (AUC_0-4) was calculated using the trapezoidal method.