Objective: To investigate the presence of Helicobacter pylori in sinonasal mucosa of patients with chronic sinusitis Design: A prospective case-control study Materials and methods: Mucosal specimens were collected from the mid-third middle meatus and lateral side of mid-cornea. H. pylori has been investigated using PCR after DNA extraction and urease test. Results: H. pylori was not found in any of the sample taken from both groups (case and control patients). Conclusion: This is the first reported study to investigate the presence of H. pylori in sinonasal mucosa in Iran. In this study, H. pylori was not determined in these sites, although its possible presence could not be excluded. Thus, further investigation on more patients and application of sensitive diagnostic techniques are recommended.