Cystic fibrosis (CF) patients commonly suffer from chronic sinusitis. Mutations of a single gene, the cystic fibrosis transmembrane conductance regulator (CFTR) gene, have been associated with CF. Functional CFTR protein is localized to the apical cell membrane, while dysfunctional CFTR is commonly found in the cytoplasm. We undertook a preliminary immunocytochemical study of CFTR subcellular localization in CF and non-CF pediatric and adult patients using a newly developed murine monoclonal antibody, TAM. Immunostaining was evaluated for subcellular localization (cytoplasmic versus membranous) and for epithelial layer (basal versus luminal). Analysis of the predominant CFTR distribution patterns demonstrated significant differences in adult versus pediatric groups independent of whether the latter were CF or non-CF (p<.0001 and p<.008, respectively), and no significant difference between the 2 pediatric groups (p = .70). This suggests that the pathophysiology of pediatric sinusitis differs from that of adult sinusitis at the level of secretion production.