The resistance of H-type and L-type BSE prions to autoclaving under EU regulation conditions for specified risk material is unknown. We employed transgenic mouse (bovinized line tg1896) bioassay to assess the efficacy of such decontamination on L- and H-type BSE. For each source, titre calculation was based on the comparison of incubation period and attack rate prior to and after decontamination. The infectious titre of L-type BSE was reduced by at least 9.40 log10 and of H-type BSE by at least 3.94 log10. In fact, no infectivity was detected for L-type or H-type BSE post-inactivation even at a 10–1 dilution.