A combined treatment of plasma andplasma derivatives by β-Propiolactone (β-PL) /UV-irradiation is inuse at Biotest for the preparation ofthe virus safe serum preserve Bisekd® and coagulation factor concentrates.The efficacy of this sterilization procedure has been demonstrated for HAV(> 8.2 log10), HBV ( 7.0 log10) and HNANB (> 4.5 log10). As HIV has become a major problem tne inactivation of HIV by β-PL/UV in human plasma was tested. Pooled human plasma was spiked with 104.2 infectious units per ml of the Gallo strain of HIV/ HTLV-III and sterilized with 0.25 % β-PL, 60 min at pH 7.2 and subsequently UV-irradiated (4 × 20 W). After treatment with β-PL alone orβ-PL/UV no infectious HIV was detectable by reverse transcriptase assay in inoculated H-9 cultures after 14 days of cultivation (> 4.2 log10 inactivation). When the virucidal efficacy of ft-PL and UV was tested separately, β-PL inactivated > 3.5 log10, UV-irradiation another 2.5 log10 of HIV, as demonstrated by immunofluorescence tests in H-9 cultures 27 daysafter inoculation.When cryoprecipitate/F VUI-concentrate was sterilized by ft-PL and UV, > 4.5 log10 of HIV were inactivated by UV and > 3.5 log10 by α-PL. The results indicate, that the combined treatment by β-PL/UV inactivates all potentialtiters of HIV, which can be expected inscreened and pooled human plasma orcryoprecipitate, used for the preparation of virus safe plasma derivatives.