Abstract :Cystic fibrosis is a lethal autosomal recessive disease characterized by defects in epithelial ion transport. It is caused by mutations in both CFTR alleles encoding the cystic fibrosis transmembrane conductance regulator (CFTR). The most common CFTR mutation found in patients, F508del- CFTR, encodes a cAMP-regulated Cl- channel that is retained in the endoplasmic reticulum (ER). In a previous work we found that calumenin, a ER resident, directly interacts with the CFTR. Furthermore, because it is a chaperon, it can modulate F508del-CFTR expression. Our aim was to depict a possible interaction between calumenin and the F508del-CFTR protein. We show here, using surface plasmon resonance, that the interaction between F508del-CFTR and calumenin is impaired in cystic fibrosis, what is likely involved in the cellular physiopathology of CF.