Inclusion Criteria:

• Patients 18 years old or older.
• Patients that meet indications for chronic rhinosinusitis based on American Academy of Otolaryngology Head and Neck Surgery clinical practice consensus.
• Patients should have twelve weeks are more of mucopurulent drainage, nasal congestion, facial pain and pressure, or reduction of smell, and inflammation documented by purulent mucus or edema within the middle meatus or anterior ethmoid region or radiographic findings of inflammation within the paranasal sinuses.
• All patients most have endoscopic evidence of nasal polyps.
• All patients must have a culture from the middle meatus, maxillary, ethmoid, sphenoid, or frontal sinus which is positive.

Exclusion Criteria: 

• Patients with Cystic Fibrosis, Primary Ciliary Dyskinesia, history of immunodeficiency, Sarcoidosis, vasculitis disorders such as granulomatosis with polyangiitis and eosinophilic granulomatosis with polyangiitis.
• Patients with a history of allergic reaction to Singulair (montelukast) or drug intolerance.
• Patients that received oral corticosteroids within two weeks of 6 month follow up.
• Patients who did not complete a pre-operative and post-operative SNOT-22 and modified Lund-Kennedy score 6 months after their surgery.
• Patients if they do not meet criteria for chronic rhinosinusitis with nasal polyps based on the AAO-HNS clinical practice consensus statement.
• Patients without a history of positive culture are excluded.
• Patients age less than 18 years old.