Sensitization, as measured by panel reactive antibodies (PRAs), occurs as a result of previous organ transplantation, blood transfusions, or pregnancy. The high-PRA levels increase the risk of complications during transplantation and may result in long time duration for future transplants. Mycophenolate mofetil (MMF) has been shown to decrease lymphocyte proliferation and antibody formation. We report the use of prophylactic MMF in preventing the formation of PRAs in a pediatric renal transplant recipient with multiple donor exposures. A four-yr-old girl received an unsuccessful living-related renal transplant in February 2003 and was subject to multiple blood transfusions in the perioperative period. MMF, 500 mg/m2/day in two divided doses, achieved suppression of PRAs to less than 20% and allowed successful renal transplantation within nine months. No side effects occurred. This approach may reduce the risk of sensitization in future potential organ donor recipients in similar situations.