The synthesis of difficult peptide sequences has been a challenge since the very beginning of SPPS. The self-assembly of the growing peptide chains has been proposed as one of the causes of this synthetic problem. However, there is an increasing need to obtain peptides and proteins that are prone to aggregate. These peptides and proteins are generally associated with diseases known as amyloidoses. We present an efficient SPPS of two homologous peptide fragments of HuPrP (106–126) and MoPrP105–125 based on the use of the PEGA resin combined with proper coupling approaches. These peptide fragments were also studied by CD and TEM to determine their ability to aggregate. On the basis of these results, we support PEG-based resins as an efficient synthetic tool to prepare peptide sequences prone to aggregate on-resin. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd.