Abstract: Cystic fibrosis (CF) or Mucoviscidosis is a recessive autossomic disease that causes a defect in the chloride transportation through the mucous membrane. A genetic mutation in the chromosome 7, area q 31, alters the protein CFTR (cystic fibrosis transmembrane conductance regulator). It is the hereditary disease that provokes more deaths among white children. Its incidence in the Caucasian population is of 1:5.000 births, being rare among the black (1:30.000) and the yellow (1:90.000) people. CF is lethal because it causes a chronic bronchopulmonary infection with progressive lung destruction, with survire, on the average, of 40 years. The diagnostic confirmation requests 2 positive sweat tests, done in different days. The result is positive when we have more than 60 mmol/1 of chloride in the child's piched sweat sample and 80 mmol/1 in the one of adult. About 1/3 of the children and almost the adults'half with CF present bilateral nasal polyposis and chronic pansinusitis. The more common symptoms are nasal obstruction, rhinorrea, anosmia and chronicle cough. About 90% of the patients with CF presenr sinusitis evidence in CT. Nowadays, surgery in patients with CF are Tare. When necessary, the functional endoscopic sinus surgery (FESS) is the choice procedure, where is tried to establish a middle meatal and maxillary ostium the widest possible. The gene therapy is the CF future treatment.