Balloon REmodeling Antrostomy THErapy Study

Inclusion Criteria: * Subjects age 18 or older with chronic rhinosinusitis of the maxillary or maxillary and anterior ethmoid sinuses * A CT scan taken after maximal medical therapy (e.g., local or systemic antibiotics, topical steroids, etc.) must show one of the following: 1. Narrowing of the outflow tract of the maxillary sinus ostium or infundibulum with mucosal thickening of 2 mm or greater of the maxillary sinus antrum. 2. Evidence of maxillary sinus air/liquid level. Exclusion Criteria: * Evidence of chronic posterior ethmoid, sphenoid or frontal sinusitis * Inability to understand the study or a history of non-compliance with medical advice * Unwilling or unable to sign Informed Consent Form (ICF) * Currently enrolled in any other pre-approval investigational study (does not apply to long-term post-market studies) * History of any cognitive or mental health status that would interfere with study participation * Previous sinus surgery or intervention including sinuplasty * Pregnant women * Severe septal deviation causing obstruction of the ostiomeatal unit * History of primary ciliary dysfunction * Hemophilia * Currently undergoing or in the past 6 months had undergone chemotherapy for cancer or radiation therapy in the head or neck region * History of cystic fibrosis * Known Sampter's Triad (aspirin sensitivity, asthma, sinonasal polyposis) * Known sinonasal tumors or obstructive lesions * History of mid facial fractures or orthognathic surgery (does not include nasal fracture) * History of insulin dependent diabetes * Not able to stop anti-coagulant (e.g., warfarin) until the International Normalized Ratio(INR) is below 1.5 * Not able to stop anti-platelet (e.g., clopidogrel, aspirin, etc.) for at least 14 days prior to study procedure * Not able to stop any non-steroidal anti-inflammatory medications and homeopathic medications for at least 14 days prior to the study procedure * Presence of nasal polyps that may interfere with the treatment procedure * Presence of features consistent with sinus fungal disease on CT or physical examination