Nasal polyps are the most common mass lesions found in the nose and their etiology is unknown. Nasal polyps from cystic fibrosis (CF) patients are histologically distinct from nasal polyps from patients without CF. It has been suggested that a mutation (G551D) of the cystic fibrosis transmembrane conductance regulator (CFTR) gene may play a role in nasal polyp formation in patients without CF. To investigate the possibility that this or other CFTR gene exon mutations are required for nasal polyp formation, the CFTR gene exons were sequenced from peripheral blood DNA derived from an adult patient with edematous eosinophilic nasal polyps and no personal or family history of CF. No mutations or deletions were identified in any of the CFTR exons. A single polymorphism (A or G) was found in exon 10, base pair 1540, amino acid 470. This polymorphism was detected in 11 of 16 subjects (69%) with edematous eosinophilic nasal polyps and 10 of 21 normal subjects (48%) without nasal polyps and was not statistically significant (p = 0.316). These results demonstrate that mutations of the CFTR coding region are not a prerequisite for the formation of edematous eosinophilic nasal polyps.