Background: Nasal polyps are common in patients with chro nic rhinosinusitis, yet, to date, little is known about the pathophysiology of nasal polyp formation. This study aimed to determine the effect of montelukast (a leukotriene receptor antagonist) as a maintenance therapy for 3 months to prevent recurrent nasal polyps, and detect the relation between cysteinyl leukotrenes (LTC4) in the recurrence of nasal polyposis. Patients and Methods: This is a non-randomized phase III clinical trial study included 40 patients with nasal polyposis either primary or recurrent nasal polyps. The study work was done in Otorhiriolaryngology Department in Zagazig University Hospitals in the period from 2010 to 2013. Who were divided into two groups (20 patients in each group) with nasal polyposis either primary or recurrent nasal polyps detected by nasal endoscopy and CT scan of the nose and para nasal sinuses. Functional endoscopic sinus surgery (FESS) was done for all patients to remove nasal polyposis then nasal polyp was taken from all patients during operation to detect the level of tissue leukotriene (LTC4). Results: The percentage of female was 22 (55%) and male was 18 (45%). Regarding Nasal Polyp, Bilateral were 40 (100%) and Unilateral were 0 (0%). There was no statistically significant difference between group A and group B regarding Eosinophil. While, there was statistically significant difference between group A and group B regarding Immunohistochemistry expression of LTR. Conclusions: Montelukast (a leukotriene receptor antagonist) appears to be beneficial in prevent recurrence of nasal polyps.