Reliable methods for determining the localisation of mutant CFTR protein in native cells from CF individuals are necessary to allow the degree of mislocalisation of any genotype to be defined and to assess the effect of therapeutic agents on CFTR trafficking. Here, we present procedures for obtaining ciliated epithelial cells from CF patients by nasal brushing and a description of protocols for immunolocalisation of CFTR. The protocols are a consensus, following comparison of some aspects of methods currently used in the authors' laboratories. © 2004 European Cystic Fibrosis Society. Published by Elsevier B.V. All rights reserved.