Mycophenolate mofetil (MMF) significantly decreases acute and chronic rejection after renal transplantation when prescribed at 2gr / day. However, circumstances arise in clinical transplantation where the does must be lowered, either to avoid drug toxicity or patient intolerance. This study determined whether MMF dose reduction was associated with subsequent risk of acute rejection. Between January 2003 and November 2004 in this prospective study all of the KTP patients received 2 gr MMF daily (control group) in combination with cyclosporine and corticosteroids and in a subgroup patients who can not tolerate the drug or their body weight with less than 60kg the does of MMF decreased to 1.5gr daily (study group). Then clinical and paraclinical outcome were compared in two groups. The primary endpoint was the incidence rate of acute rejection (AR) during the first 12 months post transplant; secondary aims were to compare patient survival, graft function, drug side effects, and other adverse events at 12 months of follow –up. A total of 224 patients (1.5 gr MMF (study group, n =109) and 2 gr (control group, n= 115) were included in the study. mean age and weight of study group were (35.20 ± 10.70 years and 61 kg) and control group were (36.29 ± 13.4 years and 66 kg) respectively. At 12 months there were no significant differences between study and control groups in patients survival (100 vs. 100%), graft survival (95% vs. 96%), acute rejection (8% vs. 9%) or mean creatinine mg/dl (1.25 ± 0.5 vs. 1.30 ± 61) respectively. In conclusion, the incidence of acute rejection for transplant recipients who underwent MMF does reduction was not higher than those who received conventional therapy.