Ovine scrapie can be transmitted via environmental reservoirs. A pool of ovine scrapie isolates were incubated on soil for one day or thirteen months and eluted prion was used to challenge tg338 mice transgenic for ovine PrP. After one-day incubation on soil, two PrP(Sc) phenotypes were present: G338 or Apl338ii. Thirteen months later some divergent PrP(Sc) phenotypes were seen: a mixture of Apl338ii with either G338 or P338, and a completely novel PrP(Sc) deposition, designated Cag338. The data show that prolonged ageing of scrapie prions within an environmental matrix may result in changes in the dominant PrP(Sc) biological/biochemical properties.