Cyclosporin A (CsA) has a narrow therapeutic window and necessitates monitoring of blood concentration. We aimed to evaluate trough (C0) and second hour (C2) level after ingestion of drug monitoring in renal allograft recipients. In this retrospective study, 12 children eight boys and four girls; mean age at transplantation 14.6 +/- 3.7 yr (ranges: 7.0-19.0), mean age post-transplant 17.8 +/- 4.9 yr (ranges: 9.0-24.0) who were transplanted >6 months were enrolled in this evaluation. Ten were recipients of a living related donor and two deceased donor grafts. While six children were receiving CsA, steroids and azathioprine, the other six received CsA, steroids and mycophenolate mofetil. Clinical course, blood pressure, renal and liver function tests were recorded. Mean C0 and C2 were 96.2 +/- 59.5 and 504 +/- 305.4 ng/mL respectively. Mean serum creatinine level was 1.2 +/- 0.45 mg/dL and mean creatinine clearance (CrCl) was 89.2 +/- 36.8 mL/min/1.73 m2. There was a correlation between serum creatinine level, CsA dose and C2 levels,whereas,there was no correlation between age, blood pressure, CrCl and C2 levels. However, no correlation was found between C0 levels and any of the above parameters. In conclusion, our data suggest that C2 levels are correlated better with dose and serum creatinine level.