Faeces from infected animals have been suggested as a potential source of contamination and transmission of prion diseases in the environment. This work describes the development of a procedure for the detection of PrPres in stools which is based on a detergent-based extraction and immunoprecipitation (IP). The procedure was evaluated by analyzing TSE-spiked sheep and mice faeces, and proved to be specific for PrPres with sensitivities of 5-10 μg of infected brain tissue. In order to analyze the shedding of prions, we studied stools from orally inoculated mice over 4-days post-inoculation and also stools from terminally sick scrapie-infected mice. PrPres was only detected in stools shortly after the oral ingestion of TSE agents. The procedure described could be a useful tool for studying the excretion of prions and for evaluating potential environmental contamination by prions. © 2008 Elsevier B.V. All rights reserved.