The invention describes compound of the 2-thiooxo-4-thiazolidinone type for the treatment of Cystic Fibrosis (CF). These new inhibitors have specific activity for CFTR. Cystic Fibrosis Transmembrane conductance Regulator (CFTR) chloride channel is mutated in CF cells. This mutation leads to a mistrafficking of the protein that is retained in the endoplasmic reticulum.