In an attempt to clarify the influence of dysfunctional bladders on renal allograft outcome, graft survival was studied retrospectively in patients with congenital posterior urethral obstruction (posterior urethral valves). Using the Australia and New Zealand Dialysis and Transplant Registry (ANZDATA), 25 index patients were compared to all other transplant recipients of the same age range. Three instances of abnormal bladder function leading to graft function deterioration were found, therefore we would recommend investigation of bladder function in all boys with congenital urethral obstruction prior to renal transplant, and as part of the work-up of graft failure, where the cause is otherwise not obvious.