Cystic fibrosis (CF) is the most common autosomal recessive disease among Caucasians. It is characterized by abnormal transepithelial sodium and chloride transport. The clinical expressions of the disorder are highly variable including nasal polyposis. Some authors have found that CF children with nasal polyposis form a distinct subgroup of patients within the clinical heterogeneity of the disease with milder gastrointestinal and pulmonary symptoms. The aim of this prospective study was to verify whether the clinical manifestations in CF children with nasal polyposis are different from control CF patients, and to identify any correlation between a phenotype of nasal polyposis and a genotype. Sixty-six CF children, aged 1-25 years, consecutively underwent ENT examination including nasal endoscopy. Twenty-one had nasal polyposis. The remainder formed the control group. There was no statistical difference in the mode and age of presentation of the disease between the two groups. The clinical manifestations (Schwachman and Kulczycki score, colonization by Staphylococcus aureus and Pseudomonas aeruginosa) were comparable between the two groups. We found no statistical difference in the repartition of genotypes between the polyposis and the control groups. Nasal polyposis does not seem to be genetically dependent, but a larger sample of patients is needed to reach an accurate conclusion.