Recent studies have suggested adverse outcome for renal allograft rejection associated with dense CD20 lymphocytic infiltrates in transplant renal biopsies. We investigated further the relationship between renal allograft survival and CD20+ lymphocytic infiltrates in renal transplant biopsies from children with graft dysfunction. Fifty consecutive unselected renal transplant biopsies were performed for investigation of acute, chronic or acute on chronic renal allograft dysfunction in 48 children aged 1-17 (median 13.1) years, at 0-155 (median 22) months post-transplantation with median follow up of 24 months post-biopsy. Seventeen (35%) graft losses occurred at 1-163 (median 49) months post-transplantation. There was increased graft loss in those with dense (>300 cells/hpf) CD20+ lymphocytic infiltrates present on biopsy (p = 0.043). Dense B-cell infiltrates were also associated with increased glucocorticoid requirement in those with acute cellular rejection (p = 0.0015). There were no significant differences in age, sex, HLA-mismatch, type of transplantation, EBV or CMV serology or baseline immunosuppressive regimens between those with or without dense CD20+ infiltrates. Dense CD20+ lymphocytic infiltrates in renal transplant biopsies are associated with adverse clinical outcome, including increased graft loss. This observation raises the possibility of future studies examining the efficacy of B cell depletion therapy in this clinical context.