Polyomavirus-associated nephropathy (PVAN) has recently emerged as an important cause of allograft failure following renal transplantation. The BK virus is the most important polyomavirus associated with this condition. The mainstay of therapy for PVAN is a prompt immunosuppressive dose reduction in conjunction with careful monitoring for BK viraemia. A number of antiviral agents have been tried to help to reduce BK viral replication. So far, there has been only a single randomized controlled study on the use of one of these agents. Pooled data from various small case series did not show significant differences in outcome. Prospective randomized studies with a standardized protocol are urgently required.