Pregnancy after renal transplantation has become increasingly common. Studies in non-immunocompromised patients have shown that pregnant women have increased susceptibility to infection or reactivation of latent virus such as BK virus. To what extent a renal transplant recipient is at risk for reactivation of polyoma virus during pregnancy remains unknown. We hereby report successful pregnancy outcome in a renal transplant recipient with a known history of BK virus nephropathy treated with cidofovir i.v. To our knowledge, this is the first published experience with a successful pregnancy in renal transplant recipients with known history of polyomavirus-associated nephropathy.