The aim of the present study was to investigate the effect of tangerine juice on the pharmacokinetics of cyclosporine A (CsA), in children who received renal transplantation. This placebo-controlled study was done on 10 kidney transplant recipients with stable cyclosporine trough levels received either tangerine (Unshio Satsuma) juice or water. Patients were given their morning dose of CsA, and then 250 ml water or the juice and 12 hr, PK investigations were performed. The main outcome measures were peak concentration and time to peak and area under the concentration- time curve. Administration of CsA with tangerine juice compared with water and didn't increase significantly in the area under the whole blood concentration versus time curve from 0-12 hrs (AUC 0-12) of CsA, (tangerine juice: 2797 ± 1361[P= 0.5], water: 3053 ± 1532). Co administration of tangerine juice with CsA compared with water had no significant effects on the AUC 0-12, Cmax and tmax of the CsA in pediatric renal transplantation.