The B-cell depleting anti-CD20 antibody rituximab has become a therapeutic alternative in renal transplantation. However, understanding of the pharmacodynamics is limited. We have therefore studied the effect of single-dose rituximab, in combination with conventional triple immunosuppressive therapy, on the B-cell population in peripheral blood as well as in tissues, in kidney transplant recipients. Forty-nine kidney recipients received single-dose rituximab. The prevalence of B cells was assessed in peripheral blood, kidney transplant tissue, and in lymph nodes. In 88%, complete depletion of B cells in peripheral blood was observed and, 15 months after treatment, B cells were still undetectable in the majority of patients. In kidney tissue, B cells were also completely eliminated. In contrast, the B cells were not eliminated in lymph nodes, although a reduction was observed. In conclusion, single-dose rituximab in kidney transplant recipients evokes a long-term elimination of B-cells in peripheral blood as well as within the kidney transplant.