Chronic rhinosinusitis with nasal polyps (CRSwNP) is one of the most frequently encountered chronic nasal diseases with a significant impact on patient quality of life. The aim of our study was therefore to investigate the association between the POSTN, IL-4, and IL-13 gene expression and the nasal polyp development. The objective of this study was to determine differential expression of POSTN, IL-4, and IL-13 genes in the mucosa and polyps of 63 patients with CRSwNP and 23 chronic rhinosinusitis (CRS) without nasal polyps (CRSsNP) when compared with patients with nasal septum deviation (n=18) who were used as controls. The expression level was investigated using reverse transcription-polymerase chain reaction assays in the polyp tissue and the mucosa of paranasal sinus collected while undergoing functional endoscopic sinus surgery. Expression of the mRNAs of all three genes, IL-4, IL-13, and POSTN, was significantly greater in the paired tissues of CRS patients with NPs or without NPs than in control subjects, with highest levels of POSTN and IL-13 seen in CRSwNP. An increased level of POSTN, IL-4, and IL-13 gene expression may be related to the development of chronic rhinosinusitis with nasal polyps, but polyp formation seemed to be associated especially with POSTN and IL-13 expression.