Traditionally, antirejection therapy in organ transplantation has mainly been directed at T cells. During recent years, the role of B cells in acute rejection has attracted more attention. In the Radboud University Medical Center (Nijmegen, The Netherlands) we performed a randomized, placebo controlled study to assess the efficacy and safety of rituximab as induction therapy after renal transplantation. In parallel we investigated the effects of rituximab on the numbers and function of B and T cells. An overview of the results, which have largely been published in peer reviewed papers, is presented below.