Sixty cases of fungal sinusitis are presented from 2 institutions, accumulated from 1971 to 2005. Fifty cases were from a large suburban general hospital and 10 from a major university referral center. Two of the 50 and 3 of the 10, respectively, were immunocompromised patients and had acute fulminant disease. This suggests that encountering the various forms of this disease may, in part, be dependent on the referral nature of the institution. The remainder were immune competent and had chronic symptoms of nasal discharge, stuffiness, and facial pain. Imaging studies frequently showed sinus expansion, opacification, and bone erosion, although no clinical or radiographic features were predictive of extrasinus extension. Chronic fungal sinusitis is principally represented by fungus ball/mycetoma and allergic fungal sinusitis. The recent literature suggests a predominance of or a predominant interest in allergic fungal sinusitis. Hyphal colonies and the presence of allergic mucin with scattered organisms are histologic observations and are the respective keys to these diagnoses. However, the etiologic role of the fungus in chronic cases is not settled. Patients with chronic sinusitis who yield positive sinus cultures only, but have no organisms visualized histologically, are not universally regarded as having fungal sinusitis. The interest in fungal sinusitis has generated a prominent role for the pathologist. An awareness of the various forms of the disease and thorough histopathologic study, including submission of all tissues removed at surgery and recognition of allergic mucin, are essential. Acute fulminant/invasive fungal sinusitis may require frozen section for adequate management.