Due to increased use of kidneys from extended criteria donors, there is an increase early use of belatacept to avoid the nephrotoxicity of calcineurin inhibitors. A belatacept calcineurin inhibitors-free regimen is associated with an increased risk of T-cell mediated rejection and opportunistic infections, particularly cytomegalovirus infection. To prevent cytomegalovirus infection, a novel anti-viral drug, letermovir, is now available. In patients who present refractory/resistant cytomegalovirus infections, it is nowadays recommended to use maribavir. However, the management of CMV infection still requires further studies. For instance, the role of anti-cytomegalovirus immunoglobulins to prevent or to treat cytomegalovirus infection in association to classical anti-viral drugs requires to be studied. The effect of belatacept on BK virus replication is controversial. There is no specific anti-viral treatment directed against BK virus. It is recommended to monitor closely BKV DNAemia and to reduce immunosuppression in case of positivity, especially in patients with high viral load or polyomavirus BKV-associated nephropathy