Summary Not only in blood transfusion, but also in transplantation of allogenous bone, infection of patients with bacteria and especially with virus is possible. Neopterin as an unspecific marker of an activated cellmediated immune response is elevated in fresh viral infection even before antibodies are detectable. Additional determination of neopterin in bone banking can further reduce the already little risk of a still antibody-negative HIV infection in a spongiosa donor. If a first HIV-antibody test is negative and serum neopterin lies within normal range, a second HIV-test six months after operation, which is otherwise obligatory in bone banking today, can be cancelled and the allograft can be given free for transplantation assuming negative results obtained by other screening criteria.