Post-translational protein modifications are responsible for much of the variety and diversity found within the proteome of any organism. Of the various modifications a protein can experience, glycosylation is the most prevalent, occurring either on Asn residues, in the case of N-glycosylation, or on amino acids presenting a functional hydroxyl group, such as Ser or Thr, in the case of O-glycosylation. Both N- and O-glycosylation transpire in all three domains of life, i.e. Eukarya, Bacteria and Archaea, although current understanding of each version of these processes is not consistent. Able to thrive in amongst the harshest environmental conditions on the planet, Archaea express proteins that remain properly folded and functional in the face of physical conditions that would normally lead to protein denaturation, loss of solubility and aggregation. In Archaea, numerous glycoproteins have been detected in a long list of species isolated from a broad range of environments. Analysis of the polysaccharides decorating archaeal proteins reveals the use of a more diverse set of sugar subunits than seen in either eukaryal or bacterial glycoproteins. Still, little is known of the steps or components involved in this post-translational modification in Archaea.