The aim of our study was to investigate the effect of tangerine juice on the pharmacokinetics of cyclosporine A (CsA), in children who had received a renal transplant. This placebo-controlled study was done on ten kidney transplant recipients with stable cyclosporine trough levels who received either tangerine (Unshio Satsuma) juice or water. Patients were given their morning doses of CsA and then 250 ml water or the juice, and 12 h, investigations of the pharmacokinetics (PK) 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 did not increase significantly the area under the whole-blood concentration versus time curve from 0–12 h (AUC_0–12) of CsA, (tangerine juice 2,797 ± 1,361 (P = 0.5); water 3,053 ± 1,532). Co-administration of tangerine juice with CsA compared with water had no significant effects on the AUC_0–12, peak concentration (C_max) or time to C_max (t_max) of the CsA in pediatric renal transplantation.