Background Despite lower mycophenolate dosage used in our patients due to adverse gastrointestinal effects and infection, we can achieve acceptable rate of acute rejection in the first year, comparable graft and patient outcomes. We therefore performed a study to examine the pharmacokinetics of mycophenolic acid determined by area under the curve from 0-12 hour (MPA AUC0-12) in our kidney transplant population. Methods The kidney transplant recipients with stable graft function who were receiving mycophenolate mofetil (MMF, cellcept®) 1-1.5 g/d or extended-release mycophenolate sodium (ERMPS, Myfortic®) 720-1,080 mg/d in combination with either cyclosporin or tacrolimus, and prednisolone were studied. The MPA concentration was measured by Fluorescent Polarization ImmunoAssay (FPIA) using Cobas Integra 800 (Roche Diagnostics®) at pre-dose (C0), 1 (C1), 1.5 (C1.5), 2 (C2), 4 (C4), 6 (C6), 8 (C8), and 10 (C10) hours after dosing. Results 152 patients were included in our study. The mean AUC0-12 was 35.91 + 14.9 ug-h/ml (7.41-89.58). The mean AUC0-12 in 138 patients maintained on either MMF 500 mg or ERMPS 360 mg BID was 35.03 + 14.81 ug-h/ml (20.89-62.72). The correlation between C0 and AUC0-12 was poor (Spearman’s r = 0.628). Limited samples using C0, C1.5, and C4 demonstrated good correlation with the full AUC0-12 profile (r2 = 0.72). Mean AUC0-12 in tacrolimus group was higher than cyclosporin group (38.27 + 15.82 vs 32.69 + 13.67 ug-h/ml respectively, P = 0.1) Conclusion Despite the reduced fixed-dose mycophenolate regimen, most of our kidney transplant patients have the MPA AUC0-12 within the therapeutic range.