Chronic feline upper respiratory disease remains a challenge to diagnose and treat. This is a case of a four year-old, female, spayed domestic long haired cat presented to the Internal Medicine Service with a complaint of chronic upper respiratory disease characterized by copious bilateral mucoid to mucopurulent discharge from both nares with productive sneezing and no ocular discharge. Her referring veterinarian had attempted repeated courses of antibiotic therapy without success in abatement of clinical signs. A full work-up for diagnosis of chronic upper respiratory disease was completed to eliminate the many differential diagnoses for this disease including bacterial, viral, fungal, parasitic, foreign body, neoplasia, dental disease, nasopharyngeal polyp, nasopharyngeal stenosis, and inflammatory rhinitis. With the results of advanced diagnostics such as serology, computed tomography, rhinoscopy, culture, histopathology, and cytology a diagnosis was eventually made of inflammatory rhinosinusitis. The patient was successfully treated with pulse antibiotic therapy and intranasal NeoPolyDex ophthalmic drops every other day, though finding a successful treatment regimen can be challenging in many cases.