Sixteen sheep and 18 cattle were followed up during 1 year to estimate the duration of immunity induced by inactivated bluetongue virus serotype 8 (BTV-8) vaccines (sheep and cattle) and a bluetongue virus serotype 1 (BTV-1) vaccine (cattle) under field conditions using cELISA and seroneutralization test (SNT). Four sheep never seroconverted. Those that seroconverted were all seronegative by BTV-8 SNT at the date of last sampling [378 days post-vaccination (dpv)]. Eight sheep were still positive by competitive ELISA (cELISA) 378 dpv. All the cattle seroconverted. At the end of the study, eight and 11 cattle were still positive by BTV-8 SNT and cELISA, respectively (335 dpv); and nine were still positive by BTV-1 SNT (301 dpv).