Background and Aim: There are various studies on the inflammatory pathogenesis of nasal polyposis (NP). It hasbeen suggested that discoidin domain receptor-1 (DDR1) and collagen type 4A (COL4A) have a role in formation ofinflammatory responses in the tissue microenvironment. The aim of the study was to study the expressions of DDR1and COL4A in NP, and nasal mucosa.Materials and Methods: This randomized, prospective, controlled clinical study was conducted on 17 patients’ NPtissue and 24 subjects’ inferior nasal turbinate. DDR1 and COL4A expressions were determined by quantitative realtime PCR. Histopathologic examinations were also carried out. Protein levels of the samples were determined usingELISA. The associations between the parameters were explored.Results: DDR1 and COL4A transcripts were found at similar levels in all of the samples. There were correlationsbetween DDR1 and COL4A mRNA levels in both the NP and control groups. There was also a negative correlationbetween extracellular edema and COL4A protein levels in NP.Conclusion: To our knowledge, this is the first study to report DDR1 expression in NP tissue. We did not find any significant differences between NP and inferior nasal turbinate in terms of expressions of DDR1 and COL4A. Prospectivestudies with large populations should be planned for understanding DDR1 role in NP.