Nasal polyps, a chronic inflammatory disease occurring in the nose and para-nasal sinuses, result from several different causes, including cystic fibrosis (CF). Forty-four patients affected by nasal polyps were admitted to the Department of Otolaryngology, Lublin University School of Medicine, Lublin, Poland, and screened for the most-commonly identified CFTR mutations [DeltaF508, G542X, N1303 K, 1717-1 (G to A), W1282X, G551D, R553X and DeltaI507] by applying the INNO-LIPA CF2 test strips. None of the patients had symptoms that allowed for the diagnosis of CF, including the negative sweat test. We detected 5 of 44 (11.4%) carriers of the CFTR mutations. All patients positive for this test were heterozygous carriers of DeltaF508. In the control group, only 1 of 70 (1.4%) cases showed DeltaF508 heterozygosity. The frequency of DeltaF508 mutation herein reported was significantly higher than in the control group (P = 0.0312) and in the general Polish population as well (P = 0.0059). Our data suggest that a heterozygous manifestation of the DeltaF508 may exist in a selected group of patients affected by nasal polyps, who have no other clinical features of CF.