Treatments for the various kinds of fungal rhinosinusitis are fundamentally different, and it is essential to obtain an accurate diagnosis of the particular syndrome in a given case. Microscopic examination of specimens is the most definite and rapid means of establishing a diagnosis of fungal rhinosinusitis. This article compares the utility of various staining and microscopy methods, presents two keys for the algorithmic evaluation of fungal cells as seen in clinical specimens, discusses practical aspects of fungal spore formation within clinical specimens, and reevaluates the role of Candida albicans in rhinosinus disease.