Allergic fungal sinusitis is a common disease that results from a hypersensitivity reaction mounted by the host against fungi living in the paranasal sinuses. We have recently treated a patient with allergic fungal sinusitis due to a Nodulisporium species. This is the first description of a Nodulisporium species involved in human disease. The genus Nodulisporium contains both dematiaceous and nondematiaceous members. These fungi occur worldwide in nature, often as accompanying conidial anamorphs of certain wood decay ascomycetes. Clinical mycology laboratories may encounter this new agent of phaeohyphomycosis.