This is a Phase I, exploratory safety study of the 480 Biomedical Mometasone Furoate Sinus Drug Depot in adult subjects with chronic sinusitis.

Inclusion Criteria:

• Diagnosis of CS.
• Female study subjects of child-bearing potential must have a negative pregnancy test and must agree to not become pregnant during the course of the study.
• The study subject has been informed of the nature of the study, agrees to its provisions and has provided written informed consent as approved by the ethics committee of the respective clinical site.
• The study subject agrees to comply with all study requirements

Exclusion Criteria:

• Known history of intolerance to corticosteroids.
• Oral-steroid dependent condition.
• Having had corticosteroids with potential systemic effect (e.g., oral, parenteral, or high dose topical) 1 month prior to screening visit.
• Subjects with acute or chronic intracranial or orbital complications of chronic rhinosinusitis (e.g., brain abscess, related problems with eyes or central nervous system).
• Known history of hypothalamic pituitary adrenal (HPA) axial dysfunction or having morning serum cortisol level at screening outside of normal range.
• Previous pituitary or adrenal surgery.
• History or diagnosis (in either eye) of glaucoma, ocular hypertension, or cataracts.
• Recent participation in another clinical trial within 1 month of screening visit.
• Subjects currently participating in an investigational drug or device study.