The TSEs (transmissible spongiform encephalopathies) are not only devastating neurological diseases but also provide a biochemical conundrum; how can a disease agent replicate in the apparent absence of genetic material? The prion hypothesis proposes that the TSE agent is a misfolded form of the host glycoprotein PrP (prion protein). However, a number of questions regarding the hypothesis remain to be addressed. We are using gene-targeted PrP transgenics models to investigate these issues. Here we discuss our recent results that examine the importance of PrP's N-glycans to the misfolding of the protein.